You might get better results by explaining what you are attempting to accomplish and why you can't do it now, as far as you know.
You can draw a reference plane in a plan view, change to an elevation view and rotate the reference plane in that view so it is no longer vertical.
A reference plane defines a flat plane, a flat plane can not be "3D"...it is 2D..it extends in two directions only. The objects that are created on it can be three dimensional but the plane is not.
To orient a view to a reference plane to use as a work plane it (the reference plane) must be named first. If you just draw one you can't use it to establish a workplane. Once named you can orient a 3D view to that plane and create objects on it.
I'm sure that if you explain what you want to do with Revit, you'll find that it can be done, you may just not know how yet.