What frame rate cap options are there?

The Frame Rate Cap setting goes as high as 60 FPS, and that holds on mobile as well as PC and console. So a phone gets the same ceiling as a desktop.

The lower caps are there for hardware that can't hold a steady rate. A locked 30 or 45 usually feels smoother than a number that keeps jumping around. Turning the limiter off removes the ceiling altogether and lets the game run as fast as your device allows.

If a lower cap still doesn't settle things, the frame rate isn't the only lever. Global illumination, which bounces environment lighting across objects, can be dropped to Low or switched off in the same graphics menu, and that takes load off the device.