You’d need two different characters, but you could do it the old fashioned way and have an extra command under every feature when they CC the MC, so instead of just MC changing, you would have:
@YOUNGMC changes into bodyColor Copper 01
@YOUNGMC changes hairColor into Black Dark
etc. and then you can change certain features (if you want to) like pigtails or the youthful face shape or whatever it might be.
That way, they’ll still look alike.