Reduced gravity is one theory you see for accounting for larger dinosaurs including sauropods as well as flying creatures. The other place you see it is in discussions of the ancient tectonic plates involving the former super continent; the claim is that the super continent itself had significantly greater curvature than the planet does at present, requiring that the planet has gained significant mass since then; that would affect gravity.
Weight is proportional to volume, a cubed figure while strength and every other measure of efficiency are proportional to squared figures, the familiar square/cube problem. You lose power/weight RATIO as you get larger no matter what you do, which is why you do not see 200-lb athletes in gymnastics. Calculations based on that idea apparently show an upper bound of somewhere between 20K and 30K lbs for anything to be able to stand up and walk in our world today. The biggest elephants are around 15,000 lbs and that's probably about one percent of elephants.
The problem with the Podkletnov experiment is that Einstein's version of what gravity is would forbid it. But then again as I noted, the USAF does not have the luxury of assuming Einstein to be right.