George's relatively smaller size in the movie Rampage is directly attributed to the limited exposure he had to the experimental serum responsible for the creatures' rapid growth and mutation.
The "Project Rampage" serum acted as a catalyst for massive biological alteration, with the extent of each monster's growth and physical change depending on the amount of the pathogen absorbed. In George's specific instance, he only received a small whiff of the potent genetic editing agent. This minimal exposure meant that while he did undergo a significant transformation into a giant ape, reaching an impressive height of approximately 35 feet tall, his development was less extreme compared to other creatures infected by larger doses.
Consequently, George largely retained the familiar appearance and characteristics of a gorilla, just on a much grander scale. This contrasts with other animals affected by the serum, such as the wolf Ralph and the crocodile Lizzie, who experienced more pronounced mutations and attained significantly larger sizes due to their greater exposure.
For more information on the film, you can visit the Rampage (2018 film) Wikipedia page.
