Marzipan is an open-source icon pack for android featuring colorful drawn adaptive icons.
The icons aren't too saturated while still being plenty colorful, feature more consistent proportions and color palette, as well as avoid being overly simplified!
Grab the apk file from here and install it. Alternatively hopefully there will be an F-droid release in the future..
In the app go to Apply tab for further instructions, you might need to download a different launcher first.