The Sultan/ruler can’t possibly be the shadow of Allah!
Although some narrations say that the sultan is the shadow of Allah on earth, according to the Quran this can’t be possible because:
Allah has no deputy. He hasn’t given anyone the right to use His authority (al-Isra 17:2; al-Muzzammil 73:9).
Adam was the khalifa/successor on earth, not of Allah (al-Baqara 2:30).
Allah doesn’t share His Sovereignty with anyone (al-Kahf 18:26).
Unconditional obedience was not even given to our Nabi (not Rasul) (al-Mumtahana 60:12).
The rulers had to be held accountable for what they did (Al Imran 3:161).