My older bunny has a massive dewlap. He has had it for a long time. I don’t exactly know if its a dewlap but yeah. But anyways he also has a fat tumor on his hind leg. I can’t tell if you can see the dewlap from these pictures though so
My bunny is a Californian neutered male and he has a large dewlap. He is pretty healthy and I have no problems with him or his dewlap. So I am not worried about it.