Custom render pass for game

I am familiar with Unity where we are able to “plugin” to the rendering engine to provide additional rendering passes, but am not finding anyway to do this within Unreal Engine. Is the only way to add a custom rendering pass to the renderer by modifying the engine code? This is to add a new rendering pass during runtime (gameplay) not for rendering out a cinematic.

If the only way to do this is by modifying the engine code, any suggestions on how best to provide this additional functionality to other developers?