Can you give them the size off the model an thay print it to suit also?
They can enlarge it to any size needed, but this will be the size of paper (i.e. the whole plan). You will need to calculate what this enlargement factor needs to be, in order to get the hull lines to the size you need.
Perhaps the easiest way to do this is print off a copy of known size. Measure the hull lines and work out the ratio of the
copy in hand:copy size wanted.
Then apply this ratio to the paper size.
And consider, how accurate you need it to be.
For example, if you want a one meter hull then 1.1 meters will not kill you.
If you need a specific scale (not always that important) then a few percent either way will not kill you either.