For 2D art, linear works emphasize lines, silhouettes, and linear contours; contrasts with art that emphasizes light and shadow & indistinct edges. For 3D art, linear works emphasize exterior contours of the form.
Scale refers to the relative size of the objects within an artwork & of the whole work relative to a viewer. A consistent scale could be used V certain elements could be emphasize by size. Also, the size of the work could overwhelm V invite the viewer.