Are you trying to do an email address change on your current ID or create a new Apple ID? Note the restrictions in the article.
Apple ID Name Change. *
What to do after you change your Apple ID or password - Apple Support * I suggest doing this before you change your Apple ID or password.
If you create/use a new Apple ID, you will lose access to some of your data and the purchases made with your existing Apple ID.
Apple ID - create a new. *
Apple ID – Create -
Apple ID - Could Not Create or Could Not Set Up iCloud message.
Apple doesn’t routinely monitor the discussions. These are mostly user to user discussions.
If you want to, you can send Apple feedback. They won't answer, but at least will know there is a problem or a suggestion for change. If enough people send feedback, it may get the problem/suggested change solved sooner. Pick the closest topic you can find.
Click here to send Feedback