depends on the fish, if talking about pure midas it depends on the variant that you have, if you have a barred midas than no it will not peel and will stay the greyish color with black barring, if you have a orange/piebald/creamsicle one then yes it will peel once it reaches a certain size, this size also varies greatly between individuals, some peel at 3-4in some dont peel till 7-8in, when i (regrettably) got rid of my piebald midas he was about 6-6.5in and had only just started to get a nice red sheen under his grey base color and stripes, i would love to see what he looks like now if the guy i sold him to still has him...
also if you talking about the midevils from petco/petsmart they have already peeled from their juvie coloring (i think they may be fed hormone stuff at the farms to color up early like oscars are but i really dont know) they will probably peel again once a little bigger but not necessarily