No call forwarding option in phone settings
When I go to settings for phone there’s no option for setting call forwarding.
iPhone 15 Pro Max, iOS 26
Question marked as
Most of the time call forwarding must be carried out with your cell carrier directly
https://en.wikipedia.org/wiki/Call_forwarding
In Europe and sime other countries outside USA you can dial the following code in Phone app
**61*nnn*11*XX#
where nnn is your voicemail number and XX is the time in seconds before going to voicemail, maximum 30 seconds.
USA is different, see the link