Black pencil lines around the model

Hello everyone,

I would like to achieve a result close to this one (https://sketchfab.com/models/64b50d4621b04ea39932edef9d36b3c4) by adding automatically the black lines around my mesh when rendering.

Notice that they are not everywhere but only on certain part of the mesh (like a quick drawing/ sketch). This can add a wonderful artistic touch especially if I want to create a game.
Could you please help me to achieve this result ?

Best,

Alex