"Tone" is a bit of a wrong word.
There are two kinds of muscle fibers, slow and fast twitch. The slow fibers are good at endurance, the fast ones are good for short-term high demand, like lifting heavy things a few times.
People who are "toned" have lots of slow twitch muscle mass, and little fat. So if you want to look "toned", do high repetition exercises.
If you want a bugger butt, do BOTH heavy/low rep and lighter/high rep exercises (just not on the same day) to stimulate both kinds of muscle to grow. Heavy squats and 'butt bridges', and lots of lunges and cable kickbacks. For fat loss, walk on a treadmill on a high incline (uphill) but stay off your toes or you'll wind up with massive calves.