How to unlock SIM on my iPhone 14 Pro Max?

Do you mean that you want to remove a SIM PIN? Or are you saying that your iPhone is locked to a specific cell carrier and you want to get it unlocked? In either case, you need to talk to your cell carrier.

If that's not what you mean "unlock", please post back and explain exactly what it is you wish to accomplish.

Regards.

Contact your carrier and ask them to remove the lock on the SIM card.