I have always had the power fantasy of the superpower of “I can manipulate anything I can understand. The better, more nuanced, and more correct my understanding, the more fine and powerful my control.”
It is essentially an int stat demipotence. Obviously, I would never achieve omnipotence or omniscience, but it would be cool to just rewrite the laws of physics because I understand how they work normally.
Also, I know better than to ever touch the Hubble constant or vacuum energy state. It would be fun to do extremely local manipulation of the gravitational constant or maybe some of the Riemann curvature constants to adjust the local shape of spacetime.