Please tell us where you saw this bird. But no, there are no mega-large species of Jay - all are similar to Blue Jays in size, some just a tad bigger. Magpies, a western bird, are much bigger and are related, but they don't look at all like Blue Jays. My guess is your bird was something else entirely. Your location may help us in guessing - also any other details you could provide may be helpful.
Randy
