Hi..
Im using a iPhone XS. I used a smart cleaner app and then after a month i realized that my old photos are gone. (Photos of my baby's birth) I have a old iCloud backup but from that can i recover the old photos
iPhone XS
If you want to restore items from an iCloud backup you have to restore your iPhone from this backup. But then all data and documents will be exactly as at the time the backup has been made. So you will have to save all new items to a computer before you restore the iPhone from the backup.
Has your iPhone been syncing with iCloud Photos, when the iCloud backup has been made? Then the iCloud backup will not contain your photos. An iCloud backup is only backing up items that are not stored in iCloud (What does iCloud back up? - Apple Support). If you have been using iCloud Photos, you need an iTunes backup to recover your older photos.
This Help page describes how to restore your iPhone from an iCloud Backup: Restore your iPhone, iPad, or iPod touch from a backup - Apple Support
But try that one, if there is a chance that the iCloud backup has saved your baby photos. Check, if iClod Photos is enabled on your iPhone. If yes, it will not work.
Recovering old photos deleted accidentally
