Glute Bridges/Hip Thrusts.
First, you have the glute bridge, sometimes referred to as the hip thrust. This exercise is excellent for isolating the glutes as best as possible while helping you gain explosive power.
To do this, place your upper body across a flat bench and then position yourself, so you are sitting on the floor a barbell across your hips. Now squeeze the glutes and raise the bar up as high as you can go. Pause there and then lower down to complete the rep.
The Glute-Ham Raise.
Next up you have the glute-ham raise. This movement is perfect for getting a good pump in the glutes, which can then bring about an increase in muscle size. To perform it, you will want to position yourself so you are face down on an incline bench with your hips at the top of the bench and your legs tangling down behind it. Note you will be in a reverse position of how you would usually sit on the bench.
From there, squeeze your glutes and lift your legs up and towards the ceiling. Hold at the very top and pause before lowering down. Repeat until the desired number of reps are completed.
If you are fortunate, you may be able to find a gym that has a glute-ham raise machine and use that instead. This would allow you to add weight, making the entire exercise more challenging.
Finally, the sumo squat is the last exercise to consider adding to your glute-building routine. To do this one, position yourself as you would if you were doing a standard sumo squat with a bar across your back.
Bend down and go as low as you can, thinking of pressing through the glutes as you do. Lower yourself down, pause and then press up to complete the rep. As a bonus, this one is also ideal for working the quads and hamstrings as well.