Is it possible to change my iCloud email address?

If your Apple ID has an iCloud email address as its primary E-mail address, then it cannot be changed.

If it has a non Apple based email address as its primary email address then it can be changed to a different non apple based email address.

Change your Apple ID - Apple Support

Unfortunately, you cannot change your iCloud email address.

You can, however, create an email alias to use alongside it, you can do this at iCloud.com ➔ Mail ➔ Settings (gear icon at the bottom of the page) ➔ Preferences ➔ Accounts

Apple ID email address or password - What to do after you change I suggest doing this before you change your Apple ID.