Quality Reduction only reduces my player sprite quality

I created a small map in tiled then imported it into Unity. A small sprite character is controlled by the player to roam about the map. I am experimenting with this for University and wanted to see the effect reducing the quality had on the game and machine. So I created an executable and before playing I chose a lower quality setting. However, choosing a lower setting results in only the character becoming more pixelated, the map graphics is completely unaffected.

I assume this is to do with Tiled?

How could I reduce the quality of the map in Unity? Or does it have to be done in tiled?