It tells you a lot about a person who chooses to ignore that kind of thing.
We had neighbours who fought and our neighbour who lived in the same house (different unit) knocked on my door to ask what to do. It sounded worse than just shouting.
We decided we would knock if we ever heard it again and go in if necessary.
They ended up moving shortly after. But doing something to protect the person possibly getting beat up was never a question of "should we?"
It was just a matter of how.