Adjusting the volume on your iOS device, while no doubt an easy task, still presents a routine annoyance: No matter what you’re watching, the translucent volume display gets in the way. Trying to alter the volume shouldn’t pervade your viewing experience -- on the contrary, it should enhance it -- which is why Apple is phasing out the clunky icon with something far more discreet for iOS 11.
According to threads on the Apple rumors site MacRumors, the annoying volume box is moving to the top righthand corner of the screen, where it will be markedly smaller. It should inhibit your view to a far lesser degree, or hopefully not at all. Here's how it looks if you're watching what appears to be Fantasia: