Many custom post types have their own archive page which doesn’t exist in the page list, but I am able to customize these pages by finding the archive’s template file. But for some other instances, I couldn’t find such template files. For example, Buddyboss’s register page such as this one:https://fedlearningcenter.com/register/
By default, there isn’t a nav bar on the page. How do I find the corresponding file or filter so I can add a nav bar to the page? I think this is a general WP question because it applies to many theme or plugins.