No. Sharpshooter (as written) requires an attack with a ranged weapon. Nothing says the attack has to be ranged. I could also use a shortbow as an improvised meelee-weapon and triggers Sharshooter (I’m mostly relying on the fact that just because I’m not using it as a ranged weapon, it still is one). But Crossbow is also heavy, allowing the use of GWM.
Thanks! Someone finally got it.