Changing apple id

Why did you create a new Apple ID.

You should use the same Apple ID for the new Mac as you used for your iPhone.

If you create a new Apple ID, you will not have any access to any content acquired (free or paid) with the old Apple ID. Apple will not merge Apple IDs or transfer content from one Apple ID to another.

ASC - Late 2012 Mac mini, macOS 10.14.6; Watch, series 3 cellular, watchOS 5.3; iPad Air 2 & iPhone 8+, iOS 12.4; TV 4th Gen, tvOS 12.4;  HomePods, audioOS 12.4 and Airport Express w/ Airplay 2

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. See Winston Churchill's response in the below discussion. Also set up Family Sharing to keep access to your apps/purchases. 

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