4 digit passcode no longer option on iphone

And what shows up when you tap "Passcode Options" when changing your passcode. You have more options than a 6 digit passcode. Post a screen shot of the options that show up after tapping Passcode Options.

Set a passcode on iPhone - Apple Support

You can still have a 4 digit passcode, unless your phone has a business or school email account on it. Then the account administrator can require 6 digits, and also other security options.