You will find a variety of foods for lunch at the buffet. Each day there will be one area that is a theme. i.e. Mexican, French, Italian, etc. There will be a variety of foods from entrées to salads.
There will also be a dessert station with cakes, pastries and other sweets.
On many Carnival ships there is a Mongolian BBQ. The lines for this on my Liberty cruise were always long and I never tried it but it was popular.
There is also a Deli and Pizza station. On Liberty there was a fish and chips station on the upper level. The deli was one of my favorites. On Liberty it was much better than on Pride or Legend. The sandwiches on Liberty had much more "inside" than on my previous cruises.
There will also an area, usually just outside by the pool, that serves burgers, hot dogs and some have brats. I found on Liberty that the burger was pretty good and my grandson consumed them every day for lunch. He is a very picky eater.
For breakfast there will be the usual variety of scrambled eggs, ham, bacon, cereal, oatmeal and "other" stuff. I tried one of the Panko coated "fried" hard boiled eggs and it was one of the worst things I've ever put in my mouth. If I had been at home I would have spit it out.
Perhaps if it had just come out of the fryer it would have been palatable but this wasn't. The best thing I found for breakfast (on just about every ship) is the omelette station. You can get a cooked to order omelette with your choice of fillings.
I have never eaten dinner in a Carnival buffet but I have walked through and the choices are fewer but looked good and there "seemed" to be a number of items that were on the dining room menu. The buffet closes around 9:30 p.m. but the Deli was open until midnight and the pizza (which isn't bad) was open almost 24 hours. The days of the midnight buffet are long gone on just about all ships and cruise lines.
BTW: There is no area of the buffet, including Pizza, Mongolian Wok, Fish and Chips, Deli or Grill area that will charge you. The only charge would be if you ordered soda or an adult beverage.
There will almost always be something to eat in the buffet area and many things are VERY GOOD and I do appreciate the variety that Carnival has. I think you will also find this to be true.
Take care and enjoy,