"A problem was detected with the TrueDepth Camera. Face ID has been disabled."

Hello,

Apple has several documents helping you with Face ID.

This Support article is specific to seeing a 'disabled' Face ID alert, and explains what to do when you see that notice or an issue with the TrueDepth camera. --> If an alert says Face ID has an issue on your iPhone or iPad Pro - Apple Support

Unless a software update solves the problem you may need to have Apple take a look at your device. Use this link to set up an appointment —> Genius Bar Reservation and Apple Support Options - Apple and this one to get a repair estimate —> iPhone Repair and Service - Apple Support