Will I be able to play PS4 version FC24 if I buy PS5 Disc?

@MUSHPARKYes, if you buy a physical disc of FC24 for PS5, you will benefit from EA's "Dual Entitlement" scheme. This means you can upgrade your copy of EA SPORTS FC™ 24 from PlayStation 4 to PlayStation 5 at no extra cost. Simply, it grants access to the game on both PlayStation 4 and PlayStation 5. So, even if you purchase the game for PS5, you'll be able to download and play the PS4 version too, as long as it's associated with the same account