Iphone 11 Pro Max back glass replacement

Hi,

I have been checking all over the internet about iphone 11 pro max back glass replacement but didn’t get a clearer information.

I have accidentally cracked my iphone 11 pro max back glass and now I want to get it replaced and I was wondering what would be the cost of it in India if iphone is still under warranty. Also, will iphone still be waterproof after back glass replacement.

I have bought this phone in US and I stay in India (Just for reference)

Thanks in advance.