[Erax]

Sure. Every hull size has its own cost, which in standard SEIV is directly proportional to its size. You can tweak this to be proportional to the size squared or some such progression to make big ships reaaaaallllly expensive.

You can also tweak maintenance costs for specific hull sizes if you wish.

But remember, 'wet' navies are not a perfect analogy. Spacegoing vessels (especially the SEIV kind that never land on a planet) do not have to worry about drag and gravity as much as seagoing vessels.