How do I recover iCloud backup On Mary’s iPhone 13

If you mean how to restore the phone by using an iCloud Backup, see instructions in Restore your iPhone, iPad, or iPod touch from a backup - Apple Support

Left2write wrote:

How do I recover iCloud backup On Mary’s iPhone

13

Restore your iPhone, iPad, or iPod to factory settings - Apple Support

Left2write wrote:

How do I recover iCloud backup On Mary’s iPhone 13

There are 2 response telling you how to recover the backup, click on the link provided in those response.