Apple - Is there a 3rd party program that can change the cursor size?

If you open System Preferences>Universal Access>Mouse & Trackpad, you can adjust the cursor size to be larger. To my knowledge, there is no third party application that will do this since it is allowed natively. Hope this helps!

Occassionally I use Mouse Locator when giving demos to help the audience track my mouse movements. Mouse Locator doesn't increase the size of the mouse pointer per say, instead it "paints a target" around the pointer when you start moving the mouse. The target makes it easier to locate the pointer location. Omnidazzle also does this, but the effects are flashier.