How is the size of a planet of a planet related to the thickness of its atmosphere?

The size of a planet can influence the thickness of its atmosphere primarily through gravitational pull. Larger planets have stronger gravity, which can retain a thicker atmosphere by preventing lighter gases from escaping into space. Additionally, a planet's temperature and distance from its star also play crucial roles in atmospheric retention, but generally, larger planets are more capable of sustaining thicker atmospheres due to their gravitational advantage.