Net demand doesn't increase, because that $20/hour came from somewhere. Increase in wages means less elsewhere (ideally, corporate profit). Total demand remains constant.

That's a macro view. Drilling down there will be some products that get more attention, some less. Say, Bezos buys one fewer yacht, and his employees switch from dollar store cat food to Chicken McNuggets. Prices will jiggle around, but there's no increase in the money supply and so no net inflation.

Data repeatedly shows that there isn't a consistent effect from increases to the minimum wage -- as expected. There are too many other factors in the price of goods, and minimum wage changes get lost in the noise.