There is a slide relax brush but is there a slide brush without the relax along with it?
The defaults of brush tends to preserve volume shape.
According to that objective, there is no smoothing, unless you change value of Autosmooth slider.
If you slide edge loops from an area where mesh is dense to an area where it is less dense, of course result is relaxing of mesh.
But for same brush with same settings, if you move in the other direction from less dense area to dense area, you obtain the opposite of a relaxing. You pinch what was at start of stroke to what is at end of stroke.