Take protein, take vegetables, take carbohydrate, take sauce--cook.
That gives you an explosive number of combinations.
The best dishes at the Chinese restaurants, though, tend to be the ones that aren't in that mold. If the restaurant keeps a dish that isn't a "combinatorics" recipe, there's a reason it stays on the menu.
You can actually see this in action at a Japanese togo place I frequent. They precook the chicken and then finish on the grill. The difference between Korean and teriyaki chicken is the sauce they finish it with.
Sweet and sour <insert protein> at Chinese restaurants has the protein cooked first and then finished when ordered with the sauce.
With fried chicken, you fry them earlier and when someone orders it, you fry it again. It’s great because double frying actually makes it crunchier and taste better.
You can mix and match as makes sense (bake chicken then grill them to finish).
If you want a whole <insert animal> it is going to take longer and cost more unless you go to a banquet place. Those banquet places are optimized for that by precooking and by have a few family dinner sets. If you order something outside that, it is going to cost you and take longer to reach your table.