Drop a manifest.json containing something like the following, and a new tab xhtml file in an empty directory, then tell chromium, chrome, or edge to load a new unpacked extension
{ "manifest_version": 3, "name": "Blank new tab", "version": "1.0.1", "description": "A blank new tab page", "chrome_url_overrides" : { "newtab": "blank.en.xhtml" } }