New Apple account

Your Apple ID is the personal account you use with all Apple products and services. It includes the email address and password you use to sign in, as well as the contact, payment, and security details that you use with Apple.

You can’t merge multiple Apple ID accounts.

See -> About your Apple ID email addresses

About your Apple ID email addresses - Apple Support

See also -> iPhone User Guide - free

https://books.apple.com/book/id1567104665