Old IPAD

if you need to change the primary email address that identifies your AppleID account, you can easily update the account to use a different email address:

Change your Apple ID - Apple Support

What to do after you change your Apple ID or password - Apple Support

You should generally only have a single AppleID account, that is updated throughout its life as email addresses and trusted telephone numbers require change.

Using an entirely different AppleID account is not recommended - as all purchased Apps and service subscriptions are forever tied to the account from which they were purchased; using a different AppleID account will lose access to these items.