To my recollection, all physical Patronus charms that we see in the Harry Potter story are in the form of an animal. However, to quote this answer the nature of a Patronus charm is that it "represents that which is hidden, unknown but necessary within the personality", which depending on the traits revealed could be embodied in many different ways.
For example, if a muggle-born wizard's Patronus were to portray strong leadership and perseverance could the physical manifestation appear as Optimus Prime?