My iphone 12 pro max double SIM & I don't have option Add eSIM?

You can find your iPhone model code by DOUBLE TAPPING Model Number option.

Then check your "Axxxx" here:

A2342 (United States), A2410 (Canada, Japan), A2412 (China mainland, Hong Kong, Macao), A2411 (other countries and regions)

Regards

Giulio

If it is a 12 Pro Max manufactured for China, Hong Kong, Macao markets (code = A2412) it doesn't support eSIMs, just two physical SIM cards.

Regards

Giulio

Devices sold on China, Hong Kong, and Macau accept two physical SIM cards. There is no eSIM on those devices.