I still don't understand,

muscle is either small or large, increases in size via hypertrophy or hyperplasia, and decreases in size via atrophy or aplasia. The appearance of musculutare is entirely dependent on the size of muscle and the relative amount of fat and overlay above the muscle that allows muscle to be seen.

In order to 'build' gluts for maximum growth then overload is necessary, progressive overload. The exercise shown to be most effective for glut activation and recruitment is full squats