chromium/chrome/test/data/extensions/browsertest/url_rewrite/newtab/manifest.json

{
  "name": "New tab override test",
  "version": "0.1",
  "manifest_version": 3,
  "description": "Test chrome://newtab override",
  "chrome_url_overrides": {
    "newtab": "newtab.html"
  }
}