MagicBand+ is basically a MagicBand on steroids.  It will allow you to play bounty hunter in the Black Spire Outpost in “Star Wars: Galaxy’s Edge“.  You will also be able to interact with all of the “Disney Fab 50 Character Collection” throughout all of the parks. The band will also become interactive during the nighttime shows such as “Harmonious” and “Disney Enchantment”.

Disney Parks Blog does not mention a price or when this additional service will become available other than 2022.