is it possible to change my Apple ID or email address?

An AppleID account is intended to be used for life. If you need to change the primary email address that identifies your account, or your secondary (recovery) email addresses or trusted telephone numbers, you simply need to update your AppleID account as necessary.

Change your Apple ID - Apple Support

Change your Apple ID password - Apple Support

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

Change, add, or remove Apple ID payment methods - Apple Support

Few of us will have the luxury of forever keeping the same email addresses or telephone numbers - sometimes these needing to be changed for a variety of reasons. However, updating our AppleID account, maintaining access to our data and purchases, is easy and relatively straightforward - accommodating life’s many changes as they occur. Using a completely different AppleID account can introduce many complications and issues, not limited to losing access to paid Apps, subscriptions and services - these being forever tied to the AppleID account from which they were purchased.

Yes you can. If you're still logged in on it you can go to settings>your name>name and email

If you're not signed in you can recover the account by account recovery

How to use account recovery when you can’t reset your Apple ID password - Apple Support

Here's how you change the email address (Apple ID) you use for your Apple Account while retaining everything in your account:

1. Go to https://appleid.apple.com and sign in.

2. In the Sign-In and Security section, choose Apple ID.

3. Enter the email address that you want to use as your Apple ID.

4. Choose Change Apple ID.

5. If you changed your Apple ID to a third-party email address, check your old ID email for a verification code, then enter the code. Learn what to do if you didn't get the email. --> If you didn't receive your verification or reset email - Apple Support

6. If you use services like iCloud or Messages to share with friends and colleagues, sign in to those services with your updated Apple ID. --> What to do after you change your Apple ID or password - Apple Support

For more details, read the document: "Change your Apple ID" --> Change your Apple ID - Apple Support

Apple says: "When you make certain updates to your Apple ID, we’ll send you an email to help you complete the update. For example, you might have reset your password, reset your security questions, or added a new email address to your account." If Apple tries sending you a verification email and you do not receive it, read this support article --> If you didn't receive your verification or reset email - Apple Support

If you find you can’t sign in, reset your password, or receive verification codes, you can request account recovery (go to this document: How to use account recovery when you can’t reset your Apple ID password - Apple Support ) to regain access to your account. Account recovery might take a few days or longer, depending on the specific account information you can provide to verify your identity.