Not able to use icloud mail or create @icloud.com

I created apple account for a family member using phone number about a month ago. After the whole setup and software updates (now running on ios 18.1) i opened icloud mail to create an @icloud.com email, it showed icloud mail is not available for your account, then opened browser there signed in to icloud.com/mail there also same error shown, then watched some tutorials on youtube and went to settings and clicked on the name went to icloud to toggle on use icloud mail on this device, but there was no button like that and the in list of apps using icloud there wasnt mail app, i have restarted iphone and reinstalled mail app but nothing helped. And in sign-in and security page there is also no option to create an new email it shows to add only existing email. Now using a gmail account as primary mail as temporary but i want to create @icloud.com email.