That's why bc is great, other wise you get one episode on PS4 that you have to rebuy or in best case upgrade for a small amount to play it on PS5. I worry about => level caps in an episode and in general micro transactions. but I kind of hope they also do loyal fans upgrades. You played FFXV you get this weapon/skin..You played FFVII, you get this, Dragon quest XI/KHIII etc...
Considering how the consoles are working right now, with the PS4 copy of the game you would be able to play the PS5 version via patch.