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 ...
To set up Face ID with your mask, update to iOS 15.4, then head to the Settings app and tap "Face ID & Passcode." ...
If Face ID doesn't appear to be working on your Apple device, start by making sure it's enabled in Settings for any features you want it to unlock.