diff --git a/api/Window.json b/api/Window.json
index 49f76414e800b8..d54942f96a127a 100644
--- a/api/Window.json
+++ b/api/Window.json
@@ -5132,6 +5132,37 @@
           }
         }
       },
+      "requestResize": {
+        "__compat": {
+          "spec_url": "https://drafts.csswg.org/css-sizing-4/#dom-window-requestresize",
+          "support": {
+            "chrome": {
+              "version_added": "preview"
+            },
+            "chrome_android": "mirror",
+            "edge": "mirror",
+            "firefox": {
+              "version_added": false
+            },
+            "firefox_android": "mirror",
+            "oculus": "mirror",
+            "opera": "mirror",
+            "opera_android": "mirror",
+            "safari": {
+              "version_added": false
+            },
+            "safari_ios": "mirror",
+            "samsunginternet_android": "mirror",
+            "webview_android": "mirror",
+            "webview_ios": "mirror"
+          },
+          "status": {
+            "experimental": true,
+            "standard_track": true,
+            "deprecated": false
+          }
+        }
+      },
       "resize_event": {
         "__compat": {
           "description": "`resize` event",
diff --git a/css/properties/frame-sizing.json b/css/properties/frame-sizing.json
new file mode 100644
index 00000000000000..0fde4f49e1a432
--- /dev/null
+++ b/css/properties/frame-sizing.json
@@ -0,0 +1,192 @@
+{
+  "css": {
+    "properties": {
+      "frame-sizing": {
+        "__compat": {
+          "spec_url": "https://drafts.csswg.org/css-sizing-4/#responsive-iframes",
+          "support": {
+            "chrome": {
+              "version_added": "preview"
+            },
+            "chrome_android": "mirror",
+            "edge": "mirror",
+            "firefox": {
+              "version_added": false
+            },
+            "firefox_android": "mirror",
+            "oculus": "mirror",
+            "opera": "mirror",
+            "opera_android": "mirror",
+            "safari": {
+              "version_added": false
+            },
+            "safari_ios": "mirror",
+            "samsunginternet_android": "mirror",
+            "webview_android": "mirror",
+            "webview_ios": "mirror"
+          },
+          "status": {
+            "experimental": true,
+            "standard_track": true,
+            "deprecated": false
+          }
+        },
+        "auto": {
+          "__compat": {
+            "spec_url": "https://drafts.csswg.org/css-sizing-4/#valdef-frame-sizing-auto",
+            "support": {
+              "chrome": {
+                "version_added": "preview"
+              },
+              "chrome_android": "mirror",
+              "edge": "mirror",
+              "firefox": {
+                "version_added": false
+              },
+              "firefox_android": "mirror",
+              "oculus": "mirror",
+              "opera": "mirror",
+              "opera_android": "mirror",
+              "safari": {
+                "version_added": false
+              },
+              "safari_ios": "mirror",
+              "samsunginternet_android": "mirror",
+              "webview_android": "mirror",
+              "webview_ios": "mirror"
+            },
+            "status": {
+              "experimental": true,
+              "standard_track": true,
+              "deprecated": false
+            }
+          }
+        },
+        "content-block-size": {
+          "__compat": {
+            "spec_url": "https://drafts.csswg.org/css-sizing-4/#valdef-frame-sizing-content-block-size",
+            "support": {
+              "chrome": {
+                "version_added": "preview"
+              },
+              "chrome_android": "mirror",
+              "edge": "mirror",
+              "firefox": {
+                "version_added": false
+              },
+              "firefox_android": "mirror",
+              "oculus": "mirror",
+              "opera": "mirror",
+              "opera_android": "mirror",
+              "safari": {
+                "version_added": false
+              },
+              "safari_ios": "mirror",
+              "samsunginternet_android": "mirror",
+              "webview_android": "mirror",
+              "webview_ios": "mirror"
+            },
+            "status": {
+              "experimental": true,
+              "standard_track": true,
+              "deprecated": false
+            }
+          }
+        },
+        "content-height": {
+          "__compat": {
+            "spec_url": "https://drafts.csswg.org/css-sizing-4/#valdef-frame-sizing-content-height",
+            "support": {
+              "chrome": {
+                "version_added": "preview"
+              },
+              "chrome_android": "mirror",
+              "edge": "mirror",
+              "firefox": {
+                "version_added": false
+              },
+              "firefox_android": "mirror",
+              "oculus": "mirror",
+              "opera": "mirror",
+              "opera_android": "mirror",
+              "safari": {
+                "version_added": false
+              },
+              "safari_ios": "mirror",
+              "samsunginternet_android": "mirror",
+              "webview_android": "mirror",
+              "webview_ios": "mirror"
+            },
+            "status": {
+              "experimental": true,
+              "standard_track": true,
+              "deprecated": false
+            }
+          }
+        },
+        "content-inline-size": {
+          "__compat": {
+            "spec_url": "https://drafts.csswg.org/css-sizing-4/#valdef-frame-sizing-content-inline-size",
+            "support": {
+              "chrome": {
+                "version_added": "preview"
+              },
+              "chrome_android": "mirror",
+              "edge": "mirror",
+              "firefox": {
+                "version_added": false
+              },
+              "firefox_android": "mirror",
+              "oculus": "mirror",
+              "opera": "mirror",
+              "opera_android": "mirror",
+              "safari": {
+                "version_added": false
+              },
+              "safari_ios": "mirror",
+              "samsunginternet_android": "mirror",
+              "webview_android": "mirror",
+              "webview_ios": "mirror"
+            },
+            "status": {
+              "experimental": true,
+              "standard_track": true,
+              "deprecated": false
+            }
+          }
+        },
+        "content-width": {
+          "__compat": {
+            "spec_url": "https://drafts.csswg.org/css-sizing-4/#valdef-frame-sizing-content-width",
+            "support": {
+              "chrome": {
+                "version_added": "preview"
+              },
+              "chrome_android": "mirror",
+              "edge": "mirror",
+              "firefox": {
+                "version_added": false
+              },
+              "firefox_android": "mirror",
+              "oculus": "mirror",
+              "opera": "mirror",
+              "opera_android": "mirror",
+              "safari": {
+                "version_added": false
+              },
+              "safari_ios": "mirror",
+              "samsunginternet_android": "mirror",
+              "webview_android": "mirror",
+              "webview_ios": "mirror"
+            },
+            "status": {
+              "experimental": true,
+              "standard_track": true,
+              "deprecated": false
+            }
+          }
+        }
+      }
+    }
+  }
+}
diff --git a/html/elements/meta.json b/html/elements/meta.json
index 66285510dcb540..f2817dac3d9d67 100644
--- a/html/elements/meta.json
+++ b/html/elements/meta.json
@@ -494,6 +494,41 @@
               }
             }
           },
+          "responsive-embedded-sizing": {
+            "__compat": {
+              "description": "`<meta name=\"responsive-embedded-sizing\">`",
+              "spec_url": "https://drafts.csswg.org/css-sizing-4/#iframe-frame-sizing:~:text=If%20a-,%3Cmeta%20name%3Dresponsive%2Dembedded%2Dsizing%3E",
+              "tags": [
+                "web-features:meta-text-scale"
+              ],
+              "support": {
+                "chrome": {
+                  "version_added": "preview"
+                },
+                "chrome_android": "mirror",
+                "edge": "mirror",
+                "firefox": {
+                  "version_added": false
+                },
+                "firefox_android": "mirror",
+                "oculus": "mirror",
+                "opera": "mirror",
+                "opera_android": "mirror",
+                "safari": {
+                  "version_added": false
+                },
+                "safari_ios": "mirror",
+                "samsunginternet_android": "mirror",
+                "webview_android": "mirror",
+                "webview_ios": "mirror"
+              },
+              "status": {
+                "experimental": true,
+                "standard_track": true,
+                "deprecated": false
+              }
+            }
+          },
           "text-scale": {
             "__compat": {
               "description": "`<meta name=\"text-scale\">`",