Both ideas are partially correct. The throttle does in fact control elevation and elevators speed, but there is considerable interaction depending on the power setting and speed at which you are flying.

Here is how I do it. I slow the airplane before turning final by both retarding the throttle and adding nose up trim (elevator). I try to keep the speed pretty slow but with a safe margin above stall. (This is something to practice at altitude especially if it is a first flight.) I generally carry a little power down final until close to the runway threshold. If the airplane is a little low, I add a smidgen of power, and if it’s a little high I close the throttle completely. If I’m too high, I go around and try again.

The secret is to slow the airplane by using nose up trim to a fairly slow glide. You can fly pretty slowly even carrying a little power if you are properly trimmed. If you simply dive at the runway the landing will be pretty difficult.

It is certainly possible to simply close the throttle and glide it in, however you still need to trim it for a slow glide. When I started in R/C every landing was power off since we didn’t have throttle control, we just flew until the tank was dry and every landing was dead stick. That still works, now there is just a better way.