Apple ID change
I gave my granddaughter ( 8 years old) my XR iPhone. I need to remove my id from the XR and put her Apple ID in. Hopefully still keeping my Apple ID on my 14 Iphone.
Question marked as
You need to follow the instructions here:
What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support
Signing out of your Apple ID on your old phone will not affect your Apple ID on your new phone. The only issue would be if you failed to sign out and then started deleting data on the old phone. That would cause data to be deleted on both devices.