And how to change the Projection Mode of a SceneCapture2D(not a Camera).
Right, so presently, SceneCapture2D does not allow using orthographic projection(I assume that is what you want). It is trivial to expand that functionality, if you are into coding. If not, make sure you vote here for this feature to be included.
You could get depth of SceneCapture2D by applying a post process material in the blendables section of your scenecapture 2d. Post process material used has to contain just one SceneTexutre:SceneDepth node, hooked up to the output.
If that is the answer, you are looking for, make sure to mark the question as resolved.
Hey, I am pretty sure these features will be in 4.13. Just wait and hope. (or try the preview or source builds)
Scene depth output from scene captures and orthographic projections are supported in 4.13, along with a bunch more scene capture 2d improvements.