Behold, my library of things you can do to sculpt an awesome butt :)
Barbell/dumbbell exercises - These are what you need to do with heavy weight if you want to make your butt BIGGER. Everything else will help make your butt rounder and firmer, but will not add significant size. These will ONLY work to make your butt bigger and firmer if you get enough protein (a good rule of thumb is 1g of protein per day per lb of your weight) and a caloric surplus (at least 200 calories about maintenance).
Cardio/plyometrics - This stuff is great for shaping your butt while challenging your heart at the same time.
Bodyweight exercises - I do these when I don’t have access to a gym. You can make these more challenging by holding heavy stuff like gallon jugs full of water.