I have added and enabled the field "expire_timezone" in the create_user form to define the guest user account expire time zone during the account creation. But this field is not showing up on the UI when we try to create a new account. Please find below the screen captures confirming the filed is added and enable but not showing up during the account creation.
We can define the guest user account expiration time zone with the fields expire_time and expire_after. But the create_user form has the field "modify_expire_time" enabled by default, this field is combination of multiple expiration options/fields and the expire_timzone filed won't be visible in if you are using the field modify_expire_time in the create_user form.
You could find the below rule defined in the expire_timezone field when you go to expire_timezone >> Edit >> Advanced Properties >> Visible If.
(typeof(modify_expire_time) == "undefined" || modify_expire_time.value == "expire_time")
The above rule states that the expire_timezone will only be visible when you select the option "Account expires at specified time..."(which is expire_time) in the Account Expiration field when you create a new account.
The rule can be edited in the expire_timezone field, but the modify_expire_time is combination of multiple expiration option and that may cause confusion with expiration time zone when you select various expiry options.
So you could use the expiry_timezone field only when you select the option "Account expires at specified time..." when you create the guest accounts.
If you like to modify the create_user form and use either expire_after or expire_time field alone instead of modify_expire_time, then go ahead and disable modify_expire_time field as shown below to customize the create_user form..
create_user form with expire_time and expire_timezone(modify_expire_time is disabled).
create_user form with expire_after and expire_timezone(modify_expire_time is disabled).