When he introduces the colossal carthorse Boxer, Orwell employs hyperbole to describe his enormous strength and intimidating size:
Boxer was an enormous beast, nearly eighteen hands high, and as strong as any two ordinary horses put together. A white stripe down his nose gave him a somewhat stupid appearance, and in fact he was not of first-rate intelligence, but he was universally respected for his steadiness of character and tremendous powers of work.
The hyperbole "as strong as any two ordinary horses put together" underlines Boxer's extraordinary physical strength. He’s not just strong, he’s as strong as two horses. This exaggeration sets him apart from the other animals and also points to his importance to the farm's labor force. He’s a literal “workhorse” for his community, valued for both his “tremendous powers” and an accompanying “steadiness of character.” Animal Farm wouldn’t have come into existence without both his massive strength and his unshakable trust in Napoleon’s good intentions.
This passage also introduces an important fact about Boxer: he’s not very smart. Strength is his main value to his community, and he has so much of it that it overshadows his lack of intelligence. This works out strongly in Napoleon’s favor, as the dictator-pig relies on being able to exploit Boxer’s loyalty. Because Boxer knows he isn’t very smart, he doesn’t second-guess any of the pigs’ actions. Indeed, he repeats the phrase “Napoleon is always right” several times. It's also important to note that his physical power, while invaluable in the short term, ultimately doesn’t prevent those he was loyal to from betraying his trust. As soon as Boxer hurts himself building the windmill and loses his enormous physical power, the pigs sell him to the knacker’s (a person who makes glue from the corpses of horses).
At the very end of Animal Farm, the pigs and the human farmers from the surrounding area celebrate the return of the “Manor Farm” to its old system of brutally exploiting animals. The other farm animals gaze in horror through the window as the pigs and farmers toast to their subjugation, and Orwell uses hyperbole to emphasize just how much the pigs have changed:
The creatures outside looked from pig to man, and from man to pig, and from pig to man again: but already it was impossible to say which was which.
The hyperbole in the statement "it was impossible to say which was which" illustrates the complete erosion of differences between the pigs and the humans. Although Napoleon, Squealer, and their fellow pigs do not physically transform into humans, Orwell uses this exaggeration to underline the moral and behavioral reversal the pigs have undergone. Over the course of the novel, the pigs have gradually adopted more and more human behaviors, a sign of their gaining power and control over the other animals. By this point, they have become so corrupted by power that their former “comrades” cannot tell them apart from their other oppressors. The pigs have begun to behave exactly like humans and, as a result, have become indistinguishable from the very humans they once revolted against.