With this setting, you can adjust the outline thickness (width) for all shapes within this shape layer. Enter a value between 0 and 10 px (default – 1).

Outline Thickness customization is available if your selected Shape Layer Type is Built-in Shapes, Geo JSON, or Node Reach. This setting is not available for KML shape layers as their formatting rules are governed by the KML style file (unless Style Override is used).