There are no specific quality restrictions on food or liquids like there are at the airport. You could certainly bring more than enough baby food or formula into the park to feed a child for the day.
You should, however, be aware that there are limitations of the size of coolers that can be brought into the parks. The exact page of the WDW website that discusses coolers can be found
HERE, near the bottom of the page.
The website states that:
Suitcases, coolers or backpacks with or without wheels larger than 24"
(61 cm) long x 15" (38 cm) wide x 18" (46 cm) high are not permitted in the parks. (Coolers required
for medication may be stored in a locker or at Guest Relations.)
So, as long as your cooler is smaller than 24" X 15" X 18", you'll be
fine bringing it with you. Most soft-sided coolers that I've seen fit
within those dimensions. If you absolutely felt like to needed to bring
more into the park with you, you could bring your food in two small
coolers, carried in by different people. This would also be fine.
Have a great trip!