What should a 24 year old Indian guy having slim body and a shrunk face who eats a lot do to become healthy, gain some weight and have fuller cheeks?

I’m not sure there is a lot that you can do. My husband is the same body type as you describe – he is very slim and has a thin face. He just enjoys being able to eat what he wants and doesn’t worry too much about it. He is late 40s and weighs the same as he did at 19. He doesn’t body build but he enjoys physical activity and is always doing some heavy lifting around the house and garden.

My advice is be thankful that you are healthy and can enjoy eating all the food. Look after your appearance if that’s what you want, by wearing nice clothes that suit your body frame. Enjoy exercise to keep you healthy and feeling good.

If you’re in good health, then what you describe is hereditary.
Ask to see pictures of your father and grandfathers in their 20’s. Do you resemble them, physically? If so, you have a good idea of what your future holds.

At 24 you may well be reaching the age where your metabolism changes, and you ‘fill out’.
If not, your best course is to do as @Stinley suggests, and embrace your thinness by enjoying your food and dressing to compliment your body type.

Just live with it for now. In 20 years you’ll look just right. When I was your age I weighed 180 lbs. When I was 45 I weighed 200 lbs. and no fat anywhere.

You are 24 so there is plenty of time for your face to change on it’s own. There are a lot of protein weight gain shakes for body builders that can give you the extra calories but beware. There are plenty of people who go this route and regret it later in life when their metabolism slows down.
What you probably need is a different hairstyle and clothing style. Look in GQ magazines to see what the models are wearing. Most of their guys are tall and slim. Buy slim pants that hug your body and slim fit shirts, for a little flare, buy a vest to go over the shirts. If you like shorts for the summer, avoid the bulky ones. They will just look baggy on you and make your legs look like toothpicks. Wear the old fashion ones that go to just above your knees but are straight leg and make sure it fits around your waist and hips well. You always want a straight narrow, clean sharp look.
What is your hair like? Is it wavy or straight? Thick or thin? Dark or fair? If you want an idea of who has a great style for having a thin face and body, look at Marc Anthony.
Growing out a chin strap beard can help add the look of some weight to your face. But don’t make it heavy looking. Keep the hair short looking like 2 to 3 weeks worth of hair growth and make sure you don’t let it grow down your neck. That just makes a guys face look dirty. And then grow a long mustache above that also isn’t to thick.

Most men don’t really fill out until they hit about 40 something, some retain their youthful shape forever but many fill out markedly in middle age.
Faces fill out, necks get thicker, etc. Just like a bull. haha
You figure if the human lifespan is around 80, one does not fully mature until about age 40.
Filling out your face is just not possible unless you deliberately become overweight.

To add to my comments about my husband. He has a light beard which helps fill out his face a little

Eat more eggs for protein. You don’t want to get fat!