I draw, and edit existing downloaded vector models, in Adobe Illustrator. It works pretty well, since it displays the printable area for any given paper format & printer.
If I specify my own universal paper size, and my Epson printer, it will display printable area dotted lines some 3.5mm inside the actual paper format full lines.
In the few instances I have made something available I have let this guide my printing area, and stated that the resulting pdf is suitable for both A4 and Letter, if printed on ordinary inkjet printers (relying on Epson margins being equal to other similar printers).
I take it that laser printers will require wider margins but won't go into that, since few builders of paper models use laser printers.