Thanks for asking about the new ECG feature.
Check here for availability in your region: ECG
ECG requires the current non-beta version of iOS and watchOS. For additional help with the ECG feature on your Apple Watch, take a look at these articles.
Heart rate notifications on your Apple Watch - Apple Support
Taking an ECG with the ECG app on Apple Watch Series 4 or later - Apple Support
If you have any other questions, please reach out to our team here: https://apple.co/HeartFeatures. If you believe that you are experiencing a medical emergency, please dial your local emergency services.
Take care.