Amateur home baker here! Usually one labeled as "chewy" will have a higher fat content and more butter. A kind of good comparison ratio is around 2 sticks/16 tablespoons/250g of butter to 2 eggs (or maybe 1 egg and 1 egg yolk) for something that's fairly high-fat and chewy. Also browning the butter is goooood. If you're genuinely curious, check out King Arthur Baking's website for a chewy, or browned butter, chocolate chip cookie recipe. Yes, the flour company. They have excellent recipes.