My iphone xs max is locked to owner

Hello ~ Unless you can contact the original owner there’s nothing you can do . It has not been properly prepared for sale or could possibly be stolen. See this information:

Activation Lock for iPhone, iPad, and iPod touch - Apple Support

Also:

The All Too Common SAD Reality of Buying a Used iPad/iPhone

~Katana-San~

Contact the owner. They are the only one who can remove Activation Lock, the Apple theft deterrent feature.

There is no way for you to contact the owner, unless they displayed a contact message on the phone.

Presumably, the "owner" would be whoever you got it from to begin with... If that's not the case, then it's likely you have a stolen device in your hands.