Do they sell anything to give my xc a beefier sound, like an exhaust tip or something? I want it to growl a little more.

RJWC makes system for the 850/800XC 

https://rjwc.se/product-category/atv-utv/cf-moto/cf-moto-850/

You can make a bit bigger end tip for the exhaust and remove some of the "walls" in the muffler will also make a bit "biffier" sound