Arrange affects the depth of the selected Objects (Points, Strokes, or Layers) in the stacking order using Bring to Front, Bring Forward, Send Backward, and Send to Back.

This produces different behavior depending upon the Grease Pencil object’s ‘Stroke Depth Order’.

When set to 2D Layers, Arrange will simply change either the order in which the Strokes were drawn or the 2D Layer order. When Stroke Depth Order is set to 3D Location, Arrange will move the selected objects either towards or away from the camera, depending on the option you choose.