iCloud Messages allows you to sync all of your messages across all your devices. This is useful because it won’t take time for Messages to download to your different devices, it will happen instantly. So here’s how to enable iCloud messages on iPhone.
How to Enable iCloud Messages on iPhone
1) Launch Settings.
2) Tap your name
3) Tap iCloud.
4) Toggle Messages.
5) Now your messages will be synced across all your devices!