The standard Hip Thrust is fantastic for building and strengthening the butt muscles.
Once you become strong enough in the standard version, there are benefits to doing the 1 Leg versions too.
If you can already do a 1 Leg Version, here is a simple way to add some resistance - hold a dumbbell on the same side as the foot that is on the floor.
•Begin sitting on a floor with a bench behind body. Ideally bench height, when seated, should be at shoulder blade height. If bench is higher, begin exercise with butt off floor.
•Lift one leg off floor and keep raised during exercise. Hold a dumbbell in one hand on the hips.
•Brace abdominal muscles and keep braced throughout exercise.
•Begin movement by breathing out and squeezing glute muscles hard whilst driving through feet to lift hips up towards ceiling.
•Shoulder blades and upper back should rotate around edge of bench as hips raise up.
•Continue raising hips until knees - hips - shoulders are in a straight line. Do not over extended lower back to lift higher.
•Breathe in and reverse motion back to starting point.
•Repeat all reps on one side and then repeat with other leg.
This is my, mostly, Personal Trainer musings and information which I hope you'll find helpful!