You can play a game on the in-game browser where you can play god and kill a whole family in a car crash, including their dog.
And you can kill dogs in freeroam.
You can kill animals and there's also a plant you can eat that makes your character hallucinate they're an animal and you can kill yourself or get killed as an animal
When you are torturing Mr. K. as Trevor in the mission called By the Book if you accidentally kill Mr. K. he is injected with a needle to bring him back to restart his heart so you can continue torturing him for information.
It's not exactly a small space so forgive me if this doesn't belong here but there's a mission where you escape from a building building with limited places to go except forward and backwards
Lester makes a comment saying that Michael needs to pretend to be a math genius with low level Aspergers for a mission, obviously said in a derogatory ableist manner.
Also relating to a stereotype of people on the spectrum being portrayed in Hollywood as math geniuses.
And you can kill dogs in freeroam.