How does the new iphone transmit the data of the old iphone?

The old and new iPhone phones need to use the same Apple ID, and then turn on the automatic download function to complete the data import of the old and new phones. The specific setting process is as follows:

1. Step 1: Take iPhone7 as an example, light up the phone desktop and open "Settings".

2. Step 2: After entering the setting interface, click the "AppleID" option in the red box.

3. Step 3: Then open "iTunesStoreandAppStore".

4. Step 4: Turn on all the switches selected in the red box, and then repeat the above operation on another iPhone to complete the setting.