I have iphone 12 pro max and it is overheating

How do you know it's "overheating"? Did iPhone shut down? Your device will regulate it's own temperature, even if it feels hot.

If your iPhone, iPad or iPod touch gets too hot or too cold – Apple Support

Ah, I see. Is it charged with a licensed cable from Apple or a Made for Apple manufacturer? Is it on a soft surface, direct sunlight, warm room, etc?