No option to use face id in the settings

The iPhone 11(not pro or pro max) of my uncle and Boss won’t start the face id, meaning in the settings, those setting to use face id for certain stuff, you can’t tap on them. They are grey‘d out and won’t do anything. Also interesting: there is no „error message“(I don‘t know the word in english. In german it is Fehlermeldung). So yeah. Please help. Thx