If your going to do a great deal of 2D operate in sketchUp, then you may too utilize it’s natural drawing surface area … which takes place to be the Ground Plane, along the XY axis lines (Red/Green).
Use the Standard View Top setting to align your orientation to this.
Anything attracted elevation has no natural background to it. And unless you setup a surface area to bring into play, you are welcoming SU to easily translate how deep into it’s 3D design area your mark is going to be put in.
By contrast SketchUp is never ever going to naturally draw the line that goes listed below the ground airplane– which is why I believe it’s finest matched for the 2D illustration.
You can constantly utilize the turn command to swing your style into elevation when you are prepared.