The largest ape that ever walked the Earth, Gigantopithecus blacki, lived in what is now China and went extinct between 295,000–215,000 years ago.
📏 Height: ~3 meters (9.8 ft)
⚖️ Weight: 200–300 kg (441–661 lbs)
📸 Image: Paleo-anthro sculptor Bill Munns with his Giganto reconstruction in his Los Angeles backyard.
The Gigantopithecus is the largest extinct primate and the gorilla is the largest extant primate. They are both primates. So are humans but we already have an idea about how big humans can get.
Edit: I should have included something on the average size of gorillas though since these Giganto sizes are approximately averages.