On a flat wing model you trim it for flat & level at about 3/4 throttle and then, on approach, you reduce height by reducing throttle. Very little elevator up or down on approach.

On a symmetrical wing you slow it down and fly it at the ground at a survivable angle and then flair in the last foot or so while cutting the throttle. In that case the flair takes up elevator, and I guess it serves as a means to slow the model, but more for spilling lift and prevernting a nose-over.

Using the elevator to slow a scale (aka: "low") powered biplane will turn it into a stalled biplane on it's side or back. You have to arrange for them to stall just as the wheels touch grass. And, in fact, one wing (upper usually) is stalled purposely at that point.

You use elevator to control pitch, but not as an airbrake or to bleed-off speed. I was taught to do flat rudder turns to bleed off height if you are too high and don't want to or can't fly another circuit of the field. Throttling down to lowest idle causes the prop to drag and helps slow a model.