Apple ID change
If I change my Apple ID on one of my devices, does that automatically change it on all my devices?
Will a change in Apple ID cause me to lose any of the data on my MacBook Pro?
MacBook Pro 15", macOS 10.14
Question marked as
If you do a name change on your Apple ID, you shouldn't lose any data. Changing the ID on one device doesn't automatically change it on all devices. The ID will need to be changed on all devices, but you have to do that.
Note the restrictions in the article.
What to do after you change your Apple ID or password - Apple Support I suggest doing this before you change your Apple ID or password.