How can I redirect link example.com/page to example.com/page.html

I have one site on unknown cms and new site that is analog on WP. I must copy all content and url also must be look like as in origin site. On WP I try make seo url, but found only one solve /%category%/%postname%.html. Origin links have no .html. How can I save origin links? Redirect link example.com/page to example.com/page.html. Help me please.