FAQ says the players will be asked to link both for the first time when the game loads. And if you Unlink later, you will restrict “just that precise and originally attached” micros .ft account.
Requiring that there is No cross-platform savingsSo the progress you make in the PS5 version is not reflected in the Xbox version. That is the situation for the steam version, such as FAQ points. As the page also notes, Horizon 5 Players will need a playstation plus subscription to the game’s multiplayer feature, and “there is no plan for disk release.”
When Sony has done it in the past, gamers are not eager to link the required account. The company actually removed the need to sign in with your PSN account for some PC versions of some games, including HELLDIVERS 2 And, recently, War And Horizon Zero Don Remester.