I'm making a movie database and need to have multiple pages per post: details, cast, recommendations, reviews (something like IMDb). I would prefer to not use any plugins if possible. I'm not new to wordpress but I don't have any clue how to do this. I was looking for help on the internet but every article was about splitting long posts using pagination. So the question is how to make multiple pages per post?
You can use a custom post type, e.g.
movies and then you can have some rewrite rule which will basically render something like this
So now you can use
$_GET['page'] to check what data you have to show.
How to rewrite the slug in WordPress? Google it.
Check this answer for rewrite rules.
If I'm understanding you correctly, and you want a single post to contain the data for multiple pages of content. Then maybe use tabs. If your theme is bootstrap based than this is super easy.