Unable to change Iphone passcode
I am unable to change my passcode. There is no setting to change it under Accessibility. Previously, there was an option but not anymore
That is not where you change your Passcode and there never was an option to change it under Accessibility.
The setting you are looking for is at Settings > Face ID & Passcode.
Set a passcode on iPhone - Apple Support
If you do not see it there, then that means you have Screen Time restrictions that are preventing the Passcode change. The location for that is at Settings > Screen Time > Content & Privacy Restrictions > Passcode Changes, and this must be set to Allow. If you are a member in a Family Plan, then it is the Organizer that can prevent you from changing your Passcode and you will not have the Face ID & Passcode option under the main Settings page.