Making sure the tile is symmetrical on both sides of the room is pretty important and will likely help you decipher what size of tile you will need to create that balance.
In my observation, the smaller the tile, the more noticeable or dramatic the look you get. It just looks busier with smaller tiles, which might be the goal.
You may luck out and find the exact color and material in the size you want. Sometimes what is available on the market or for your budget is different than what you want.