Yes, it's getting confusing with all these 'I'm the biggest' claims, but LG is now claiming that its 77-inch curved 4K UHD OLED TV is the world's largest. Of it's kind of course, because all the qualifiers have to be present: a 4K UHD resolution, an OLED panel, and a curved profile.
For those uninitiated, Samsung also has a curved 4K UHD OLED TV that the company claimed to be the first of it's kind (it was indeed announced earlier), but this is only a 55-inch set. At 77 inches, LG is right too to claim that its TV is the largest so far. Both parties are happy.