There are plenty of poly people who are kinky, plenty who are vanilla, and every shade in between.
Polyamory is simply a framework for managing multiple relationships. Those relationships can involve whatever sexual practices you want, if everyone agrees and is into it. Group sex is not a defining feature of polyamory, nor does every poly person participate in group sex or any other kink. However, poly and kinky practices are not incongruent with each other.
There is a long "Master Thread" on the topic here: BDsm
If you do a search for other terms that interest you, I am sure you will find some other discussions that may be helpful or illuminating.