I’ve recently decided to give brioche a try. The best resource I’ve found is BriocheStitch.com by Nancy Marchant (Ravelry)(Instagram). She has a brioche class on BluPrint, tons of patterns on Ravelry, and several books on Amazon. I own the Knitting Brioche Essential Guide on Kindle.
Her website is super helpful in providing a good primer on working with brioche, a reminder of how the stitches work, and details on more complex ways to use brioche. I still recommend getting the book or watching a good YouTube tutorial.
Even if you feel comfortable with one color brioche, there are additional variations that will keep even the most talented knitter challenged.