Have considered character specific outfits for example dva's academy skin in overwatch. You know just some unique outfits that some characters actually wear besides their regular one in their respective IPs. Maybe they can even be worn by other characters too.
Now that I think about it you basically already have done it before with princess Leia'a bikini may. Maybe you all could drop other outfit like that just every once in a while not every single update or something, but yeah that's cool yall have thought about, great game yall've got on your hand here!