I have updated my phone but facial recognition is still disabled?

What was the result when you followed the guidance in the Related Article above your name on this page, that you were reading just before you posted here? If the Related Article doesn't answer your question please post back with more details about the issue and another user in this user-to-user forum will try to help.

Note step 2. in the related article, which says to contact Apple support to get your phone repaired if other steps don’t resolve the problem.