Iphone 12 pro

Best to return the phone for a refund.

Unless you can contact the original owner and have them release the lock on the phone, the phone will remain totally useless.

NEVER buy a used iPhone unless it powers up to the "hello" screen.

Cissi123 wrote:

Bought a used iPhone 12 pro but the previous owner forgot to log out of in clod when he reset, it has no contact with the owner, how should I go about restoring it?

You don't, you need the original owners information. And if you can't contact the owner then the phone is useless.