How can I access/recover my old Apple Account on a new iPhone?

Old phone has his previous id. We were unable to sign in with this id on new phone because the phone itself was damaged beyond use and he didn’t know any of his passwords, he always relied on his phone for the passwords. So we were unable to access his actual Apple account because every means needed to try to reset the password that he couldn’t remember we’re all in accessible because he didn’t know the password to his email account, his Apple account and the phone number linked to it was destroyed in that phone. So when new phone came, it would not let me proceed Setting it up without putting in an Apple ID so I created a new one just to get the phone set up I thought I would then be able to sign him in to his previous Apple account, where all of his items are stored in the cloud, but it is telling me that that ID is taken. I don’t understand because it’s his previous ID why he can’t have access to it on this phone.