How to back up imas SMS of iPhone 12?

The problem is how to back up iCloud SMS on iPhone 12. Automatic backup.

ICloud is a cloud backup function launched by Apple, which is divided into manual backup and automatic backup. Automatic backup. When the iPhone meets the three conditions of accessing a stable power supply, connecting to a wireless network and keeping the screen locked, iCloud will automatically back up the data in the Apple phone. Manual backup, turn on iPhone, click Enter Settings, iCloud, Backup, turn on iCloud cloud backup, and click Back Up Now, and iCloud will back up all the data in your phone.