Is it good to do a 301 redirect to .html?

Question

Search Engine Optimization

Self-written engine, I like to do everything with my own hands.
And now I have all the links right in the engine protected along with \.html - that is, not as a suffix, but as a direct part of the url.
I suspect that for promotion it would be better to make a mirror without .html with a redirect - this is more convenient for the user, and for promotion, the size of the site doubles at once (and search engines love big sites)
And the question is - is this so? Or is it better to leave it as it is - immediately with .html, and when you enter without an extension - a 404 error?

Answer 1

There is no difference with or without html. Search engines don't like duplicate content and love unique content. If one page can be displayed both ways, then do a redirect from one to another, or 404. The main thing is content.