So i was just wondering if when you buy something dose it work like how John gets his bozka dose it have its own item thing or is like a legit in game item

Exclusive SWD items and cosmetics hats are different things. If you buy a hat, it will allow you to have it in-game. Just do /give-items in-game and a chest will generate next to you.

The Black Box is a custom item made for John specifically, that's why it's unique.