The command ‘set view equal xy‘ forces the unit length of the x and y axes to be on the same scale, and chooses that scale so that the plot will fit on the page. The command ‘set view equal xyz‘ additionally sets the z axis scale to match the x and y axes; however there is no guarantee that the current z axis range will fit within the plot boundary. By default all three axes are scaled independently to fill the available area.
See also xyplane.