Changing to a new Apple ID / email address

Change information in Apple ID - https://appleid.apple.com/

Change your Apple ID - "Follow these steps to change the email address that you use as your Apple ID." Plus special instructions if your Apple ID ends with @icloud.com, @me.com, or @mac.com

https://support.apple.com/HT202667

Change your Apple ID password - https://support.apple.com/HT201355

What to do after [or before] you change your Apple ID email address or password - https://support.apple.com/HT204071

"After you change your Apple ID email address or password, you might need to update your sign-in information with any Apple services you're using." - Or if you're seeing persistent disabled messages or repeated requests for the password to your previous AppleID.

If you didn't receive your verification or reset email - https://support.apple.com/HT201455

From the article Limnos posted a link to:

If you can't change your Apple ID

If your email address ends with @icloud.com, @me.com, or @mac.com, you can't change your Apple ID to a third-party email address.

To avoid the emails, you would have to create a new Apple ID. There may be some data loss, but you can minimize it. If syncing photos with iCloud, ensure Optimization is turned off in Settings/Your Name/iCloud/Photos and/or in Photos/Preferences/iCloud. Then make sure full resolution photos are on the device/computer. When signing out of iCloud, if asked whether you want to retain data, choose yes. Messages conversations will be lost if they are addressed to the ID. See the article below for other places that the old ID should be removed. Also set up Family Sharing to keep access to your apps/purchases. Also see Winston Churchill's response in the below discussion

Apple ID – Create

How to transfer all files from one iCloud account to another

Apple ID email address or password - What to do after you change

Family Sharing

Family Sharing - Set up

Family Sharing - Use your own Apple ID for Family Sharing

Family Sharing -What types of content can I share?

Family Sharing - If you don‘t see your family‘s shared content

Family Sharing - purchases and payments

Family Sharing - Hide and unhide music, movies, TV shows, audiobooks, and books