I’m surprised that no one has mentioned the obvious. Trim the aircraft for slow flight before beginning the approach. Unless the wing loading is really high, operating at a higher angle of attack will slow the airplane down. Operating approximately 30% above stall speed is the way full scale aircraft are landed and it works for models as well. If the idle is set reasonably low (3000 rpm or less) the approach speed can be controlled with the trim. If this doesn’t work, the problem isn’t too much power, it is too much weight.

While propeller changes, cg location, etc. effect drag a little, the determining factor of approach speed is wing loading. High wing loading equals high stall speed equals high approach speed. Low wing loading equals low stall speed equals low approach speed. It’s really as simple as that.