i want to change my existing icloud email adress
as the title says
iPhone 12 Pro Max, iOS 14
Question marked as
Icloud mail address is an Apple ID signed in a device iPhone , you can change the Apple ID see the above article on this page .
If you are talking about the complete mail address once an Apple ID is created its permanent , however an alias can be created for iCloud mail address Use email aliases on iCloud.com - Apple Support