Flux uses the excellent Heroicons project for its icon collection. Heroicons is a set of beautiful and functional icons crafted by the fine folks at Tailwind Labs
There are four variants for each icon: outline (default), solid, mini, and micro.
Control the size (height/width) of an icon using the size-* Tailwind utility.
Flux has a special loading spinner icon that isn't part of the Heroicons collection. You can use this special icon anywhere you would normally use a standard icon.