To ensure everything gets moved over to the new phone.

 

Make sure that the personal iCloud apple account is signed in without any errors and Back Ups are enabled.

 

Force A sync back up on the iPhone just before you switch phones to get everything.

 

Instructions here:

Back up iPhone using iCloud

  1. Go to Settings > [your name] > iCloud > iCloud Backup.
  2. Turn on iCloud Backup.

iCloud automatically backs up your iPhone daily when iPhone is connected to power, locked, and connected to Wi-Fi.

Note: On models that support 5G, your carrier may give you the option to back up iPhone using your cellular network. Go to Settings > [your name] > iCloud > iCloud Backup, the turn on or off Backup Over Cellular.

  1. To perform a manual backup, tap Back Up Now.

To view your iCloud backups, go to Settings > [your name] > iCloud > Manage Storage > Backups. To delete a backup, choose a backup from the list, then tap Delete Backup.

Note: If you turn on an iCloud feature (such as iCloud Photos or Contacts) in Settings > [your name] > iCloud, its information is stored in iCloud. Because the information is automatically kept up to date on all your devices, it’s not included in your iCloud backup. (See the Apple Support article What does iCloud back up?)