New Passive Mob for the End: The Great Sovereign

My idea consists of creating a new End mob, but not a common one, but a giant whale in End colors, with bright purple eyes, that will fly over the End world, passing over the island and moving through it, swimming freely. It would be necessary to defeat the dragon to then be able to leave and free the great sovereign whale. This contributes to a lore that the Dragon tried to take its place and imprisoned it, but the player frees it, and this completes the story of what the End and the dimensions would be... All dimensions are the same, like a large lasagna, on the top layer is the overworld, where everything is more alive, a little further down in the core is the hottest place, and at the end of everything is the End, the end of everything, the great abyssal sea, which is why the portal is on the ground and dark, and also the reason why there are flying ships in the End, and the fruit plants of the chorus look like distorted algae. And with that, the lore would be resolved; there doesn't need to be anything in the abyssal sea, because it is an abyssal sea. It would also be very interesting to see a giant mob flying around the island; there could even be a secret interaction: if the player revives the dragon, and the whale is passing by in the distance, the whale will release a pink sonic scream, in the same style as the Warden, and it ends up killing the Ender Dragon, showing it who the true ruler of the End is.