Hello, search for MYW HS9L TV mount for SONOS Arc or Vogels Sound 3550 (is a universal TV mount for soundbars) or Flexson TV mount for Sonos Arc. These mounts are all flexibly adjustable.
With a 40 inch screen yes, the larger the screen the less the angle will be as the TV will touch the wall before it reaches the maximum possible support...
I find this bracket a little unstable and the bracket cannot be pulled out enough for swivelling, my 65" TV was immediately up against the wall.
For me, the bracket is too small for a 65" TV. I have a Vogel 3450 wall mount, which is much more stable and the TV can be swivelled 45° without any problems.