This is the PlayCanvas implementation of How to render outlines in WebGL.
See a PlayCanvas editor project you can run or fork here: https://playcanvas.com/project/753116/overview/outline-post-process.
The code in this directory has an engine-only implementation of the effect. To run it, run npm install and npm run start. Then go to localhost:8080.
The effect is in outline-post-process.js. It requires the setup of a second camera and a second render layer to re-render the scene and capture a normal buffer. This is handled in index.js.
The editor version of this effect also automatically creates the second camera/render layer as well, so all you need to do is attach the script to your camera.