how do you lot game share on ps5?

Your PS Plus comes with it too, so whoever uses that console can play online on your sub. If you want the same in reverse, your friend has to do the same thing on your console with their account. Each person picks one console.

you sign in with your account on their console, go to Settings, Users and Accounts, Other, Console Sharing and Offline Play, and turn it on. then sign out and let them play on their own account - your digital games stay playable there. the bit worth knowing is you only get one console set up that way at a time, so doing it at a mate's house quietly knocks your own out of it and you have to go and switch it back on at home.