I've seen Parise multiple times in person, sometimes standing right next to him. He is not close to my 6'+, but he is stocky, and I'm sure, like most players, has enormous thighs, which weigh a lot.
The heights on most athletes are usually on the optimistic side, but the weights are usually pretty accurate.
Kaprizov's size should not be a big issue, but we'll see. There are all sorts of player who kill it in lesser leagues, but their game doesn't translate. Hard to argue with KK's development trajectory right now, though. He done everything you can ask for without being in the NHL.