Keep in mind there’s really only a few actual pages in WordPress. Most URLs are getting redirected to index.php, parsed for the request information, and then processed accordingly. They are mostly posts in the end, which are pulled from the database and displayed according to one or more template files.
The reason that’s important is because it means you can’t really be sure where a “page” is coming from. It could be a post, a page, a redirect rule, a custom post, etc.
So you’re left with digging around a bit. There’s not a clean answer I know of.
When you load the page, can you click “Edit” in the admin toolbar?
If it is represented by a WordPress post behind the scenes, then it has a post ID. Another technique is if you inspect the page and look at the classes added to the main article, you may see a clue as to it’s ID, which will help you track it down. Note that not all themes implement the post classes correctly, so you may see nothing at all.
Once you have the ID, you may be able to tell where it’s coming from, even if you have to look at the row with that ID in your database (wp_posts).
Its possible those pages do not have actual posts behind them and are being generated by the theme or a plug-in. Do they persist when you deactivate all plugins and change themes? If so, turn them back on one by one until you find the culprit.