We have several sets of badges that we call "badge groups" around themes like Marine Life, Around the World, Black History, and more. Those badge groups are available to you and you may access them when setting up programs/challenges for your site.
When setting up a badge within a program/challenge, you will see many options for "badge groups," like this:
If you click on the name for a badge group, you will only see badges available within that group. Typically when we add a new set available to any library or school, we will add the badge group to all sites.