This is such a useful feature and it sucks it didn’t come sooner. I don’t wear a mask when I go out in public but in school I have to wear one, and usually get yelled at for the second I have to put my mask down to unlock my phone. This is really convenient and glad Apple finally integrated it.
When you install the update you are prompted to enable this feature and recalibrate Face ID. It will still work, mask or not, but apparently you now have to also add glasses