For the Destroyer, it's two-meter height wasn't a problem when entering doors. Its main problem was its two bulging arms slowing it down. Not in a sense of weight, but through interference.
Even though it had enough strength to destroy doorframes with ease, it still needs to focus enough force to achieve that. For low-rank Destroyers, casually bashing doorframes isn't possible. Also, it doesn't have enough brain cells to be able to think of entering sideways. And when it evolves to a higher rank, it doesn't even need to think of crouching since it can already wreck simple doorframes.
After widening the doorframe through brute force, the Destroyer entered the backroom and wildly searched for human presence. Storage boxes were tossed aside with every swing of its arms. Shelves were shoved to the ground after getting bumped slightly causing stocks of miscellaneous materials to scatter on the floor.
Clang, clang!