To unlock your iPhone from its carrier, you'll likely need to contact your carrier directly to cancel your contract.
To set up Face ID with your mask, update to iOS 15.4, then head to the Settings app and tap "Face ID & Passcode." ...
It's a surprisingly difficult question for them to answer, apparently. I've contacted them via email and phone with the same basic question: "If I cancel my account before the contract is up and pay ...