I don't think there is currently a way to blow up all planets and moons to that size. In fact, by default, the sizes of bodies in the game are already exaggerated—just not to that big of an extent. This is a good suggestion though.
As for the Earth's axis, there is a way to change that. In fact, there is a way to change any celestial object's axis. Select Earth and open its properties tab. Then, click on the "Motion" tab and scroll down until you see a box/slider that reads "Obliquity." This controls the axial tilt of the planet.