In my games ship sizes simply grow with time as the economy and research progress, this seems like a very natural progression.
Historically speaking this is absolutely correct.
Ville de Paris 1850 version not 1764, a behemoth ship of the line in her day 5302 tons
USS Maine of Havana fame, launched 1889, displaced 6789 tons
HMS Dreadnought first of the the new generation of capital ships 18000 tons 21000 fully loaded
USS Missouri of Tokyo Bay fame 40820 tons.
As technology has permitted the size of the capital ships of their day have grown to take advantage of it. Everything else follows apace as well. Consider a modern Ticonderoga class Aegis Cruiser of the US navy even with the design philosophy discounting armor as no longer practical due the destructive power of modern weapons still displaces 9800 tons fully loaded, quite a bit larger than the battleship of a hundred years earlier, the Maine was launched 92 years before the USS Ticonderoga.