If you want something classical, you could look at Schleich or Papo toys, you find them in some toy shops.
Designed for 75mm figures, they have a few fantasy subjects (dragons, trolls etc) but also large dinosaurs (some of the small raptors are really good, but the T-Rex is enormous).
But there is also a huge cerberus, taller at the shoulder than most 28mm figures, hefty, and about 4 inches long. Would be quite a beast if summoned.
I got one a few years ago for Ancient Greek fantasy settings - it towers over all my figures, and is big even when compared to "Wargods of Olympus" figures.