WordPress page may only load for visitors coming from Facebooks Ad?

Yes, it is possible to add a code snippet to the page that checks the referrer and either loads the page, or displays a different message / redirects the user to a different page if the referrer is not the one you are looking for.

If you like, you could adapt my plugin that detects traffic coming from www.remarpro.com: https://github.com/sterndata/wp-referrer-modal