Can you send Money internationally using Apple Pay?

Maybe, depends. Because the function to send money uses Apple Cash, which is only available to U.S. citizens / residents, whoever you are sending money to, must be a U.S Citizen / resident to have access to Apple Cash.

If they are not a U.S Citizen / resident, and don't have Apple Cash, you cannot send money to them over Apple Pay.

See here: Set up Apple Cash - Apple Support

To send and receive money with Apple Pay, you must be at least 18 years old and a resident of the United States