This guide will let you know how to select PS4 or PS5 versions of GTA 5 on PS5. You have to follow the simple instructions in this guide to do so.
When you are on the home screen, you will need to go to the GTA 5 game and tap on the more options icon next to the Play Game button. Then you have to choose the version option from the drop-down menu.
You will see both versions of GTA 5 on PS 4 and PS 5, so you need to download both of these versions. If you download the PS4 version, you can only play with PS4 friends. If you play the PS5 version, your PS4 account will be migrated to the Playstation five and will not be available on the PS4 version. So now you have to make a new account on the PS4 version.