How do I make a new email

You can add aliases for your existing Apple ID, or you can create a wholly new Apple ID, or you can change the email address associated with an existing Apple ID and that possibly to a newly-created Apple iCloud email address.

You got here from a custom email domain article—the Related Article linked above—and which is a way to use Apple email servers for your own email domain; to use Apple as an email ISP.

Creating a new Apple ID is not without its issues too, and there is no means to transfer purchases or subscriptions from an existing Apple ID to a new Apple ID.