How do I unlock an iPhone 15 Pro Max that is Locked to Owner?

Are you the original owner of this phone or did you buy a used iPhone? If you bought a used iPhone, which is locked to owner, ONLY the owner who originally set up the phone can unlock it. If you don't know them or can't reach them, the phone is useless to you. The ONLY way you get Apple to help you unlock the phone, would be to present the original purchase receipt, with the phone's serial number clearly printed on it. If you don't have that, they won't help you.

If you bought a used iPhone read this --> The All Too Common SAD Reality of Buying … - Apple Community

If you are the owner, you need to enter your Apple ID and Password.

If you are not the owner, you need to contact the owner and get the information to enter the Apple ID and Password of the owner

Do you get an error message when you try to enter your information?

I see that the OP started a duplicate thread.

Owner locked 15 pro max - Apple Community