Does the placement of the Sonos Arc matter?

I believe that it would make a difference for the reason stated above, and it would move your Arc a little closer to your seating position which would improve your ability to hear the height effects from the upward firing speakers. I move my Arc to the front edge of my media console when I watch movies.

Yes that’s what I mean would that make any difference?

Not sure what you mean exactly by “front” or “middle” but some have suggested to place the Arc on the center front edge of the top of a media stand to avoid any interference from the sound reflecting off of the media stand’s top surface.