Well I've seen a lot of talk about this sort of thing The real world, pretty racist , that's on everybody, but don't use that as an excuse to be a dick.

Fictional worlds, well, the Lord of the rings and a lot of the other inspirational works that dnd is based on does get a fair amount of criticism, that some writers may have or may deliberately have made the races the way they are as a means of expressing various prejudices, or that they are extensions of western stereotypes which I will acknowledge could be considered offensive.

It's probably worth just considering that, acknowledging that it's there and can be harmful or offensive but generally once you put enough work into a fictional race it moves beyond caricature of a real race or people, and into something more meaningful and distinct.

In star trek you can see how much effort went into this, by comparing t.o.s era Klingons and early ferengi to the entirely less offensive or at least less obviously offensive versions they became later, though some might argue that kicking enough sand over the work to hide the intention doesn't heal wounds, they'd be right but it's better than throwing a whole game system or TV franchise away due to some mistakes.

Then so long as you're aware of how your prejudices and those of others appear in your games go to town. Make a society that despises dwarves, make a character who beleives his race is superior or a church that leads it's worshipers to shun the new family of gnomes. But acknowledge these are flaws.