To win a casino jackpot is a life-changing situation. To have any chance it's necessary to make a deposit and play with real money. Every casino has a prize pool with all jackpot games. Each one of them has different big prize and you can choose which game to play.
However, there is nothing 100% sure that you will win the jackpot. Some casinos are known with more big winners, others have huge monthly payout and there is no guarantee that you be listed on any of them.
You can only try to win, but what will happen at the end is not clear. That's the main reason to play responsibly and make some personal limits.
The jackpots are mostly available on the slots machines. They have progressive prize pool based on the number of bets on each game. Other solutions are jackpot tournaments, but they are contests. Also, you can use a raffle with a huge prize for first place, it's again game of chance that you can try.