Not really, a few things that may help: the rulers (at the bottom of the core parts window) can be dragged around and won’t appear on the pcb. Vias can be positioned by changing their coords in Inspector, traces between them will produce shapes. You would need to delete them and the associated traces when the pcb is finished otherwise they will appear on the pcb. What I would probably do is use Inkscape to make an svg of the outlines and placements that you need and then import that as a silkscreen image. The svg editors are more suited to what you want than Fritzing. The problem may be getting rid of the silkscreen image when the board is complete though (I don’t know if there is a way other than editing the files to delete a silkscreen image, but editing the .fz file should do it as that is what loads it.) Easiest of all may be to make a custom part with the shape you need and insert that in the sketch, and delete it later. That would require learning to create parts though and that isn’t an easy subject.
Peter