Working out is just as much a mind game as a physical one. Your ankle/calf stretch will become more natural if focusing on keeping the heels flat on the floor.During warm-up, using light or bwt squats, that ankle/calf area will become more flexible. Actually when working into heavier weight on the squats, the heel tend to be planted strongly on the floor. Athletes are helped from getting a better stretch from flatfooted squatting. Among the other full benefits of serious squatting.
If putting a BB plate or 2X4 (preferred) under the heels , than more focus will be on the quads and somewhat away from the glutes. Even can relieve back stress and balance for some. Will see the difference in shape and size. Good Luck.