I have a custom 70" x 22" entry bench off my garage. I am adding a cushion with fabric but am wondering what size pillows to put across the back. I have material draped on pillows and the seat for a visual (photo attached) but wondering if the pillows are to large.(16") I am also attaching a photo with jackets hanging to give a better idea of the space and see if the pillows appear to large.

Should I stick with same size pillows or taper the pillows with different sizes to create a visual triangle?

I am open to any suggestions or ideas.