CS2 has drop systems too but they work differently from Twitch drops in other games. You can get weapon drops just from playing matches regularly though the selection is fairly basic compared to what you can find on the market. Cases are the main way most people get skins outside of buying directly. I looked through this
website when I was figuring out how the CS2 item system works and it explains the different ways skins enter the game and how pricing is affected by supply in a simple and clear way. Good starting point if you are coming from other games and want to understand how CS2 handles drops and skin distribution differently