In e.g. qgis, you can use blending modes, which (may) improve the map substantially. From the mentioned link, it is described as: it essentially multiplies the colour values of your layer or feature with those sitting beneath it, then divides it by 250. The impact of this is that darker areas of the basemap appear much darker, whilst lighter areas are less impacted.
Does gmt do any of this blending behind the scenes, and if not, is it possible to do?
In qgis, you can first make a hillshade/slope of a raster and then apply the blending to the shillshade/slope that is then plotted ‘above’ the original raster.