If the creator allows it, community members can create their own circles.
On the Web
Go to the community page
Simply click the + or + Create new circle tab on the left side panel where you can find all the circles
Fill in all the details and click Save
On Mobile
Go to the Circles tab on the bottom of the screen
Click the notebook icon on the top right corner > Start a new circle
Note: The default circle is where all new members will be automatically added.
The private circle is where only people you invite will see it.