The biggest Chronicle creation was Eeza Ugezod, who was a bit bigger in his second, Death Commandos incarnation than in his first Regiment of Renown appearance. But these two Grenadier miniatures are bigger still.
This one is about the size of a Chronicle ogre, and he'll make an excellent ogre in D&D (in any case, I like to use the humanoid distinctions to indicate size rather than species).
The chieftain in the horned helmet originally rode in a wolf-drawn chariot. I still have the bits, but my teenage self saw fit to mount some Citadel orcs on the wolves for Hordes of the Things. And there they remain. I have more use for a grumpy chieftain on foot than a chariot-rider.
As you can see, the latest additions tower over their lesser kin: