Highlighting mesh boundary edge

Hi, I am trying to achieve the result

Screenshot 2021-04-21 at 9.21.04 PM

Searching, I closest I have come across is EdgesGeometry which highlights every single edge, but what I am looking for is just the boundary edges.

Please help me out guys

Have you already tried OutlinePass? This approach is based on post-processing and demonstrated by this demo: three.js examples

Cool. That slipped me. Thanks!

That worked but I have gizmos rendered as a portals on top of scene. Adding Postprocessing just messes up the depth. Is there any other way it can be solved?