iCloud email

No, you can change your Apple ID email any time; You will keep the same account. See this Apple support article—>Change your Apple ID - Apple Support. It is your iTunes account that “owns” your purchases; your Apple ID is the way you access your account. You can change your Apple ID for your account, just like you can get a new credit card if yours is lost or stolen, but keep the same account.

If your iCloud email is your Apple ID when you change it your Apple ID will change also. If your Apple ID is not an Apple (icloud, mac, me, etc) domain it won’t change.