There are many types of weight gain. But in gaining, you gain water weight, fats, muscles, and so on.
Sources for weight gain
Eggs
Chicken
Brown rice
Banana
olive oil
Milk
Nuts
Butter
chicken
Red meat, and so on.
When you start eating these things, you gain weight but not muscle.
For example, when you eat a potato with curd, you gain a lot of weight. Another example is drinking banana shakes after your workout.
When you eat a proper diet then you start gaining but here if want muscles then lift heavyweight. Then you gain weight as well as muscles.
And on all your workout days, make sure you are in a calorie surplus. It means you take 500 more calories than your daily recommendation. So you can take a high protein diet.
But if you are on pro-level then you add some additional supplements. Because it gives you more energy. So you left more weight and became more powerful.
Because protein supplements give you instant energy and digest easily, you can use more supplements to increase your performance.
Example- Whey protein, you can buy any brand. Because protein is protein, there is no issue.
Heavy exercise
When you take a high protein diet then you must do hard work. Because if you store your energy then it makes you ill and bloated. So you can do a 5-6 day workout and one day rest.
On rest days, you decrease your refined carbs, such as white rice, white bread, and so on. Because your body stores fats.
But make sure you can eat a high-protein diet that helps you maintain your body energy. At last, you can eat healthy fats like nuts, cheese, whole eggs, fatty fish, and so on.
Drink plenty of water:
The main point is that you drink at least 4-5 liters of water per day.