Purchased Apple iPhone XS Max Dual SIM with FaceTime from Amazon UAE

To begin with, the only iPhones that can accept 2 physical SIM cards are those sold in China, Hong Kong and Macau.

If you bought a phone that takes to physical SIMs you will have to take it back to the country where it was originally sold for service, warranty or otherwise.

It's a gray market phone. If it was sold in the UAE it was done illegally as FaceTime is regulated by law there and selling iPhones without those restrictions in that country is a violation of UAE law.

Secondly, no matter where you bought the phone, the warranty is ONLY valid in the country where it was originally sold.

You will not get warranty service (or non warranty service) in India for a phone that was not originally sold in India.

There is no international warranty and your is only good in the US.

The warranty is only good in the country that the phone was originally purchased in. Did you buy it from Amazon directly, or from a 3rd party seller on Amazon who may have sold you a grey market phone that was intended for sale in a different country. You can tell the country the phone is intended for from the model number. If it was a UAE model phone then the warranty is only good in the UAE.