I have it right in the game intro that, with a very few exceptions as noted (sexualized violence being one), anything goes.
And thus far in my current campaign the
players have at different times (infrequently) brought in-character racism, child-killing, and torture to the table; along with slavery (as in, the PCs were the slave-sellers), mass murder, and the occasional execution. And that's just what the PCs do to the outside world; there's a whole other list of what they've done to each other over the years.
Anything goes, and as DM there's many a time I don't have to add very much; though parasitically-reproducing creatures have shown up a few times.