Manually add a .xml sitemap

Is there a way to manually add an .xml sitemap file like one created with https://www.web-site-map.com/

I’ve tried all of the wordpress plugins and none of them work. About 1/3 of them like the Yoast SEO sitemap is not working at all. Another 1/3 it seems creates an XML site map with posts despite the website having no posts, they included categories when the site only has pages and there is no way to change the functionality. Finally another 1/3 creates a BAD xml sitemap that includes pages with a low priority and don’t set the main pages with the right priority.

I have full control of the server.