Some people argue that Iron Man is planet level due to blocking the power stone beam. This is especially popular in Narutoforums.
People use the fact that Star Lord, Drax etc also survived power stone punches to argue against this notion. Although I don't think this argument works. Thanos only used light Power Stone attacks on the street-mid tiers to knock them out, while he used a continuous beam on Iron Man while he had killing intentions judging by the fact that he stabbed Tony the first chance he got.
But what about the fact that Gamora's statement that the bigger the target, the bigger the Power Stone surge? I asked this on Narutoforums and they said that Gamora was only referring to passive releases of energy like a sigle tap and also that Thanos couls control the stone with IG, so that he can adjust the intensity of the beam.