I’ve been Googling for an answer to this and have yet to find much of use. I have seen plugins that will say “pick the page for showing X” and “pick the page for showing y”. Then if the page is example.com/mypage1 they can do things like example.com/mypage1/subset/detail/finedetail. What I want to know is how I can do this with one of my plugins?

I am thinking of a specific use case where a plugin might have a lot of data to show via the front end. I know some use a shortcode to output but not all. Some seem to use the page as the building block for their permalink structure. I want to do that too.