Why did those twin get big all of the sudden

that’s their superpower, physical enchantment/ strength.

I thought their power is displacement since the royal keep telling them to send his guys back

Its part of it, maybe cause they are twins they have two powers but need each other to activate them.

But heir power have nothing to do with twin since they most likely born before the redstone crashed

But everyone was born before the redstone was crashed?
sorry, i had trouble understanding this sentence