Complex sentence: Unusually for new-kingdom art the Pharaoh and his Great Royal Wife are depicted as approximately equal in size, which together with Nefertiti's image used to decorate the lesser Aten temple at Amarna may suggest she also had a prominent official role in Aten worship.
Split into simpler sentences: Unusually for New Kingdom art, the Pharaoh and his wife are depicted as approximately equal in size, with Nefertiti's image used to decorate the lesser Aten temple at Amarna. That may suggest that she also had a prominent official role in Aten worship.