Exchange my new inactive iPhone 12 pro max with iPhone 13 pro mac

This is primarily a user-to-user support forum; other Apple users like you.

If you purchased directly from Apple, see: https://www.apple.com/shop/help/returns_refund

If you purchased from an Authorized Reseller, check with them.

Check with the reseller and see what their refund policy is.

You can trade it in but they won’t do an even swap.