Once your cleared for the approach you can use that function to extend out the runway centerline.
If ATC told you go out by 30 miles etc, you would not use the raw data but would make a PBD. Place, bearing distance.
Or ATC may say something like maintain this heading and intercept UM577 west of the VOR, in which case you need to make the anchor point or the aircraft would proceed directly to the VOR.
All this stuff is covered on the type rating course, it really is best if you learn it as part of the course or you will only cause yourself problems down the line.