Outline

Add an outline on all objects of the layer having the effect. This won't work well if shown on top of the background color of the scene. Be sure to use an object acting as a background or a floor.

Use Thickness to set how wide the outline is and Color of the outline to choose its color. Applied to an object, this is a common way to highlight a selected or hovered item.

Reference

All effects are listed in the effects reference page.