I think you are mistaken. Legend rank doesn't give you an extra plot. All of us have two plots and that's that. I am hero rank and I only have two plots.
*3x1 It adds an extra plot to each world to what you already have, in your case you had one, so it gives you another.
Donator-Premium: 1 plot Legend-Hero: 2 plots Herobrine- 4 plots I think this chart is accurate, but I don't really understand the 3x1,2,3 thing I (Herobrine) have 4 plots so idk