Ranked rewards? What literaly all games do is just reward you with specific cosmetics (banner/profile pic) so you can show off you did well at a season. Obviously the rewards is, well... your rank? What else are you playing for then to be top x in the world?
If alternate models, should they be in, would be tied to ranked performance, it would piss off so many people they'd probably lose a lot of sales on it. I hope I don't have to explain the stupidity of excluding the vast majority of players from your content. If you're going to go that way, at least try to ask money for it so you get something out of it. Loads of fighting games do that all the time and nobody cares as it's not gameplay-related, so there's a precedent.