Depends on the autopilot. There are some that are as rudimentary as a “wing leveler.” They only have control of the ailerons and can level the wings and maybe make turns. Other systems have control of all three major control axes and are integrated with the navigation systems so they can do things like climb to an altitude and level off, turn to a heading, or even fly holds and approaches.
They do require training on the part of the pilot to use in flight.