If I am restricted on a friend’s Facebook page, will all posts not be able to be seen or just the ones from the time you are set to restricted?
According to the Facebook documentation:
When you add someone to your Restricted list, they'll only be able to see your Public content or posts that you tag them in.
So after you're on their restricted list, you won't see past or future content unless it is marked as 'Public' or you are tagged in the post.