They're well worth the investment but only if used properly.
The glutes are a hip extensor but also used in abduction (moving the leg to the side) and external rotator (butt clenching). If you use BB during these type of movements you'll get an added resistance that'll help with muscle growth.
Good movements to use them with are hip thrusts, lateral walks, deadlifts, hip abductions etc. Just ignore what the majority of Instagram models do as they're largely idiots who have a nice ass due to genetics. Wearing BB during biceps curls etc makes no sense whatsoever (yep, I've seen that happen).
Also, there's much debate as to whether you should wear the band around your ankle or knee. Because of the force vectors I'd suggest above the knee to begin with (less pressure on the knee joint) and drop down to the ankle as you become stronger.
As a female you're at much higher risk of ACL injury so form is everything. If bands force your knees to drop inward during ANY exercise, ditch the band and get stronger in that movement first... then add in the BB.