My Root box is quite big, because it’s the french edition so it includes the Root automatons, and the first expansion (Lizards and Otters).
I think the smallest box i have is Complots which is a french version of Coup, with squared cards, it fits in one hand.
Kingdom Death: Monster may be my biggest if we’re counting the volume of both the game box and the miniatures box. If not Twilight Imperium is big but I think the big Galaxy Trucker-and-expansion in one box is taller and might be bigger overall.
Smallest for me is probably Codenames. Unless Set counts.