D&D 5E What's Your Favorite 3rd Part 5E Book Of 2021?

[Reynard]

For the players and DMs that I know that use this, it is more of a pick a race, any race, and the DM will just find a way to incorporate it into the world. So it's a player's fancy and whim, more than an actually used setting.

The quote that I was replying to claimed the books 200 races were incorporated into its setting. I was curious how.