In a DLC trailer for Total War Warhammer 2, it describes a ship that was sunk by the main monster as “60 cannons and 200 souls.” How big of a ship would that be by the naval standards of European navies by the Colonial/Napoleon era?

That is a weird ratio of cannons to men. Age of sail warships were heavily manned because they needed to have sailors available to shoot the guns, sail the ship, tend to repairs, give orders, and shoot small arms fire all at the same time in battle. A 24-pounder long gun takes a crew of 12 to fire. Assuming the ship is only fighting one side at a time (30 guns), that is 360 men for the guns alone. Even assuming lighter guns that take half as many men still gives very little crew left over for sailing, etc.

For comparison, the USS Constitution (1797), which was a heavy frigate had 52 total guns and a crew of 450 men (and 30 boys). So the ship in question is armed as close to something like a 3rd Rate Ship-of-the-Line with the crew of something like a Sloop-of-War or a smaller Frigate. It doesn't really make sense. Especially since Warhammer Fantasy has a kind of Late Renaissance/Early Modern level of technology which generally would mean heavy guns requiring more men. Also less advanced sail/ship design, again requiring more men.

Long story short, you'd need something around 3rd-Rate Ship-of-the-Line sized to hold that many cannon.