There is this cool picture by
u/hiplobonoxa, the redditor made a scale comparison of all dinosaurs in game. If you are reading this, thanks for your picture!
View attachment 126582
If you look at the large herbivores, you could see the dreadnoughtus and brachiosaurus share almost the same height, with the brachi being a bit taller with its distinctive skull shape. The downside is that the brachiosaurus is visually larger with the extra bulk. The dreadnoughtus is very well built, but is skinnier looking than the brachiosaurus. If they wish to give it the biggest dinosaur that ever lived title, maybe having it scaled up to to look at the mamenchisaurus in picture eye to eye would work. The mamenchisaurus will still have a pretty long neck, and having the dreadnoughtus scaled juuuust a bit more than the brachiosaurus makes this statement of being the largest dinosaur in the JW universe more believable.