If you include film models, they are the largest to date.
The largest film Titanic model/prop was the stern sinking prop from James Cameron's "TITANIC" which came in at 60ft in length. But that was only a stern section made prop. Then there was the 45ft "hero" model of Titanic, again built for James Cameron's "TITANIC". This was the full ship. The largest FULL ship model/prop was the one made in 1979 for the film "RAISE THE TITANIC" which was 55ft in length.