Heck no!
Well, not always at least. Yoda was the runt of the litter, and while the breeder said he would probably be 4.5 or 5 pounds, he's a full grown 6.5 to 7 right now, bigger than both his Mom and Dad. A lot depends on how and what you feed your Yorkie. We fed him a bit TOO well when he was a baby.