Both cleans and snatch are the ultimate compound exercises working your calves, quads, glutes, traps, shoulders, triceps and I’m sure a few other muscle groups in there as well. They’re great for building mass and expanding your shoulder width beyond what ‘normal’ lifts would allow you to gain.
When I was fighting I’d work these lifts, and variations of each, into my workouts as often as I could. Explosiveness is key when you’re trying to knock someone out, I think that goes without saying, and these lifts are maybe the most effective exercises out there to accomplish this.
As I incorporated these lifts into my workouts my power definitely began to increase, but so did the size of my shoulders and traps. Both lifts use different grips and positioning that most other exercises. The snatch uses a much wider grip than any other lift which will help broaden your shoulders, while cleans use both a push and a pull in the upper body which is uncommon among most exercises.
If you want to push your shoulders to the next level I suggest you start to put some cleans and snatch into your workouts. Have fun with it too, there are tons of different variations you could use, I suggest starting with the originals, perfecting your form, and then broadening out from there.
Let me know how it goes!