Upgrading iPad
Is there any Apple service available to India regarding upgrading iPad Air 4 to iPad Air 5 ???
There is no direct upgrade path for iPads anywhere in the world. If you want to buy a new iPad, you buy the new iPad.
In some countries, Apple offers Trade In options to use an old device to get a discount on a new one. but it's not a direct upgrade. You get a gift card you can use to lower the price on a new device.
In India unfortunately there is no such option. You can sell your iPad privately, and use the money towards the purchase of a new iPad model.
Apple Exchange Offer - Trade In - Apple (IN)