How to recover deleted photos from recently deleted folder?

See this help page: https://help.apple.com/iphone/11/#/iphf14943e

Recover a deleted photo or video. In the Recently Deleted album, tap the photo or video, tap Recover, then tap Recover Photo or Recover Video to move the item to the Camera Roll or, if you use iCloud Photo Library, to the All Photos album.

To recover multiple photos and videos, tap the Recently Deleted album, tap Select, tap the photos and videos you want to recover, then tap Recover.

Then the photos are gone for good. Recently Deleted is keeping the photos for 30 days and then deleting them finally.

If your photos have not been syncing with iCloud Photo Library, you can try to restore your camera roll from a backup, if you still have a backup of your iPhone from the time, before you deleted the photos.

The device backup does not include the photos however, if you are using iCloud Photo Library. Then it will not help to restore the device from a backup.

See: Restore your device from a backup