OK. I understand what you mean, then.
The tool that you need is the other Divide button – the one at the bottom of the Deformation menu. When you click that button, it doubles the polygon count in all unmasked parts of the model. Following this up with the Smooth deformation will smooth out the vertices.
Edge sharpness is a function of the number of polygons in the model and how close their relative sizes.
What you are seeing happen with native ZBrush objects is actually one of ZBrush’s subdivision algorithms at work. It doesn’t affect the geometry of the model, and as a result it won’t look the same when exported unless the exported model is given subdivision in whatever program it is taken into. You can actually see the true geometry of a native ZBrush object by turning off SV and SH right underneath the tool preview.