Characters in fiction can eat all sorts of things. In historical fiction, they might have period-appropriate foods like medieval bread and stew. In romance novels, they might enjoy romantic dinners with fine wines and chocolates.
In fiction, it really varies! Sometimes characters have elaborate feasts with fancy meats and desserts. In adventure stories, they might eat simple campfire-cooked meals like roasted nuts and dried meat. In sci-fi, they could have synthetic or alien foods.