Turn on Messages in iCloud on your iPhone, iPad, or Mac
Sign in with the same Apple ID on all devices
On iPhone or iPad, go to Settings
Tap your name
Tap iCloud
Turn on Messages
On Mac, open Messages
Go to Messages
Click Settings or Preferences
Click iMessage
Turn on Messages in iCloud
Wait for messages to sync
Open the Messages app on the device you want to view them on
Check the conversation list for synced messages
If messages do not appear, make sure the device is connected to Wi-Fi or cellular data
Make sure iCloud storage is available
Make sure Messages is enabled under iCloud settings
Restart the device if needed