If you cannot find them in “deleted notes” folder, then they are gone for good.
Seriously, backup notes somewhere that has more robust management system. Apple notes doesn’t even support undo, let alone safely guarding your notes.
Shake the phone (hard) quickly side to side 2-3 times and you can undo anything you did in Notes to your heart’s content.
But you’ve got to turn on “Shake to Undo” in accessibility settings.