I'm new to sculpting in blender and I've came across this problem where any diagonal sculpt that I add to my cylinder looks 'grid-like'. However, horizontal and vertical sculpts are fine. I've tried to find solutions online but seemed few have discussing about this issue. Is there a way to make the diagonal sculpt smoother? The cylinder was divided 6 times up to a few million polycounts already. Any help is appreciated.
Try enabling Dyntopo and turning the Detail down. Dyntopo adds geometry as you sculpt, and lower detail means smaller pieces of geometry, hence more detailed. In the image below, the bulge to the lower right has the default level of 12.00, 5the one to the upper right has 0.50 and the one to the left has 2.00.