If I buy I phone 11 in USA will it works in India

You'd have to check with your carrier in India to ensure the US version is compatible with their network. Please Note that iPhone warranty is NOT international and should you have any issue with your US purchased iPhone, you will need to bring it back to the US for service. It's ALWAYS best to buy your phone in the country you live and will use it.

Depends on either the phone being unlocked or it your carrier will temporarily unlock it. Don’t let them trick you into buying minutes and data from them, you’ll end up with a nice 1k Bill.