The best workout plan for big muscles would depend on your individual fitness goals, current fitness level, and overall lifestyle. Generally, it is recommended to incorporate weight training with compound exercises (such as squats, deadlifts, bench press, rows, and overhead presses), supersets, drop sets and other advanced techniques. It is also important to ensure that you are getting sufficient protein in your diet to support muscle growth, as well as adequate rest periods between workouts. Additionally, it is important to include cardio and stretching to maintain flexibility and help with recovery.