While in full allosaurus form, Drake's own size increases, making him bigger than a Pacifista, and he retains this size while in hybrid form. He is also granted a strong biting ability that can even damage the heavy armor of the aforementioned Pacifistas, which are said to be stronger than steel. His tail is also a powerful weapon, capable of slamming people with great force.
The following events are Non-Canon and therefore not considered part of the Canon story.
This is the first Ancient Zoan power seen in the series, and the first to be officially named, 420 chapters after its initial appearance.
The depiction of Drake's full-beast form in his first appearance is largely based on the outdated model of the Allosaurus and other theropods that became popular in the 20th century and have since been corrected. Oda's model in particular is late 20th century.
The hands of all theropods were strong, but like birds (the theropods' modern cousins) they were usually positioned facing sideways in a "wing stance", while older media depictions positioned them more like hands. They could pin a prey animal and their arms were far stronger than those of a human's, but they could not clench to grip like Drake is shown doing.
Many depictions of Drake fully transformed have his stance too far up, with the front end raising up. In reality the stance of the allosaurus was much lower at the front, as is the case of almost all theropods.