Input Color :Color - Provides the fill color, often supplied by the Toon brick.
Outline Color :Color - Can be set as a constant or can be varied by connecting a brick network.
Outline Threshold :Float - Adjusts the width of the outline. The outline will vary in width depending on distance from camera and degree of surface curvature.
Examples
In a Material
A simple example:
Toon Outline is often combined with the Toon brick:
This method is used in the Orange Toon Shader Mixer Preset: