Glowing Assets by Button-Press?

I’m trying to make a ‘scent view’ in which important assets glow when the bound button is pressed and held by the player.
Currently I have the widget set to show on pressing X, the camera changes to first person and a border + darkening filter appear on the screen. All I’m missing is for nearby interactive objects to have glowing halos. If anyone has played the Witcher 3, that is an excellent example of what I’m trying to achieve.
Anyone have any ideas about how I could do this?

Thanks so much!

Postprocess, custom depth material and meshes.
Then change postprocess “strength” to 0 or 1 on button press.
There is simple tutorial about custom depth material.

Some links:

Instead of making outline increase brightness (add something like 1,1,1,1 to RGBA) of meshes with custom depth.
So your material will be much less complicated than makin outline.

Thank you very much for your help! I have it all set up now except for getting my postprocess volume to react to button press. How would I go about that? So that the volume turns on when I press E, and off when I release E.
Thanks so much again.