The grid visual cannot be changed, but the grid visual does not limit the building area. RoadRunner does not prevent the user from placing assets outside of the grid visual.
That said, 2000 x 2000 m is a recommended maximum map size. RoadRunner's performance may start to have noticeable decreases for maps larger than 2000 x 2000 m, depending on the machine. In actuality, RoadRunner's map size is only limited by a computer's memory.
