I am planning to buy iPhone 11 Pro in US and move to India.
If I buy the iPhone and add AppleCare+ with theft and loss coverage, would I be covered in India?
Apple legal agreements are at https://www.apple.com/legal/sales-support/
The theft plan is specific to each US state, so you might have to read the entire document so you are comfortable with it.
Just as in the past, the plan may not cover you outside the country of purchase per the contract wording for the state of Minnesota plan.
4.1 Coverage Area
We may restrict your coverage benefit to the country where the Covered Device was originally purchased subject to section 6.2.
Assuming you have any coverage event other than loss, the new coverage looks the same as in the past. Covered wherever you are, but if you seek service outside US you either have to ship it back on your dime or accept local services if offered.
As a side note, there's no theft and loss coverage program available in India. See Apple's India Sales & Support at https://www.apple.com/in/legal/sales-support/