If they have room to seat you, you can order whatever you like. Bar (Magic / Wonder) or table. The days of a fixed price meal are over. You can still pay a flat rate and choose from a Prix Fixe four-cruise menu (limited options) or go a la carte totally. Or even add a dish to your fixed price for whatever the stated a la carte cost is.
You will pay 18% auto gratuity on a la carte items.
The free Platinum meal can be used as a $50 credit against your meal if ordering a la carte. ($50 is the current flat rate meal, unless I have that incorrect).