@Anonymous
Unfortunately Fusion doesn't yet support break lines in the Drawing Environment. Your best bet at the moment is to Export the Sketch you used to create the Body or Component into DXF format and work with it in AutoCAD or your favoured software for editing DXF's. To do this you can right-click the sketch in question and select Save as DXF. If you haven't got a clean sketch your best bet then is to create a new one and use the "Project" tool to project all relevant items onto a flat plane, then this sketch can be exported into DXF.
Other option is of course to scale the drawing differently so that it fits on your page but I am presuming that this will then not display very well for your needs.
Given the drawings are generated from views of your 3D models it makes sense seeing as the Drawing Environment is still being heavily developed. If it isn't already a suggestion in the Idea station I'd recommend making one for creating break lines in the drawing environment - would be very useful!!
Regards,
David