Custom post type’s posts are not showing anywere but in xml sitemap

There are several tutorials like this one from WPBeginner that tell you how to create, then display a custom post type. You may need to create templates, and decide where and how they will display.

You could list them as menu items, then use that menu in a sidebar using widgets.

You could also use a plugin like Display Custom Post to list them in a more graphical way.

Good luck!