When we select pictures to remove them from "Recently Deleted," we get this warning before the final step:

The pictures are in fact erased permanently.
About iCloud Backup: You would have to get to the backup quickly, usually within a day, before the backup is replaced by a newer one. However, if you did have iCloud Photos enabled, then the iCloud Backup wouldn't make an extra copy.
Perhaps you have shared your pictures with friends-- then you could get them to send copies back to you.
Unfortunately, if you don't keep your own backups to an external drive, then there really isn't any place else to look. To back up your pictures you can just plug in an external drive, select the pictures, and use Share>Save to Files. Alternatively, you can backup to a computer:
Transfer photos and videos from your iPhone or iPad to your Mac or PC
If you haven't done one of those backups, then your remaining pictures continue to be in peril.