Why is Face ID and passcode option missing in iPhone settings?

Preventing Passcode changes with Screen Time will remove the option from Settings. The location is at Settings > Screen Time > Content & Privacy Restrictions > Passcode Changes. It should be set to Allow. If you are a member of a Family Plan, then the Organizer may have control over that option.

Do you have a corporate email account set up on your phone?

If it's under management by a Mobile Device Management system, you may not have some options as those are controlled by the system administrator.

Are there any Screen Time restrictions enabled on your iPhone? Do you have a work email address on the phone?

In iOS 18, it is further down in settings. If you still can't find it, contact apple support here. iPhone - Official Apple Support (Because remember, we are not apple.)

"Why is Face ID and passcode option missing in iPhone settings?: why missing face id and passcode option in my iphone settings"

-------

Search for these Settings:

What happens when you type Face ID and Passcode into the search box on top of settings?

It says “No Results”