How do I change my apple id on my new iphone 11

See Change your Apple ID https://support.apple.com/en-us/HT202667. 

And see What to do after you change your Apple ID or 

Password https://support.apple.com/en-us/HT204071 (supplementary to what the fist link says)

And FYI, see  iCloud: About your @icloud.com, @me.com, and @mac.com email addresses  https://support.apple.com/en-us/HT201771

Post back if you have questions about what you can do if your Apple ID (1) is a third-party apple ID or (2) ends in icloud.com, me.com, or mac.com. 

How to Change Your Primary Apple ID Phone Number on an iPhone

What to do after you change your Apple ID or password - Apple Support

1. Sign out of Find My.
2. Sign out of your Apple ID.
3. Enter your new Apple ID and password.
4. Sign in with your new Apple ID.