is Sri Lanka support blood oxygen monitoring sensor Apple 9

Yes, the Blood Oxygen App is supported in Sri Lanka.

click here ➜ watchOS - Feature Availability - Apple

ECG and Irregular Rhythm Notifications are not supported there, however.

The official Apple website that lists the features that are supported and what countries they are supported in says it is supported. Not sure what more you want than the official Apple website.

If you are buying this watch in the U.S the yes, Blood Oxygen is not supported on U.S. models due to ongoing legal proceedings, but this currently is only on watches bought in the U.S. since the option was removed.

If you buy the watch in any other country outside the U.S. that supports the feature, the blood oxygen sensor is enabled and functional.

click here ➜ About Blood Oxygen availability - Apple Support

But if you are buying the Apple Watch in the U.S., the model sold in the U.S. does NOT have the oxygen sensor support.

I only mention this because we get a lot of posts asking about buying in the U.S. and taking the Apple Watch to a different country.