OK, so we’re gonna suspend some of the the laws of physics, that might get in the way.
It’s not unusual for horror movies to have giant/mutated critters. So. . .
IF. . . it were possible for a spider to be as big as a pig or a cow, and not collapse under its own weight, what kind of sound would it make. I’d have to think its mouthparts would make some kind of clicking chattering sound. Maybe just a lot of drooling sounds as it was about to inject something to turn me into soup.
I thought of this while watching a doc recently called “Monster Bug Wars.” As the bugs were battling, there were these cool dubbed-in growling, roaring sounds as they did the close-ups.