How to make an HTML page like a 404 page in WordPress?

Question

htaccess

I have a 404.html file at the root of the site, the theme is TwentyTwenty. Deleted the 404.php file from the TwentyTwenty folder. In the .htaccess file, I specified "ErrorDocument 404 404.html", the .htaccess itself is also in the root folder. It would seem that everything should work, but no.

Answer 1

I don't think this can be verified. You have a CNC there and all requests are sent to index.php, where WP decides whether such a page exists or not. The server is no longer involved in this and cannot issue 404.html.
Why not paste the html code in 404.php?