You can enable it using instructions on this site https://smartwatchchart.com/how-to-enable-ecg-and-blood-pressure-on-galaxy-watch-4-easy-method-no-pc/
Here is trick to enable ECG and BP. Check out this link https://smartwatchchart.com/how-to-enable-ecg-and-blood-pressure-on-galaxy-watch-4-easy-method-no-pc/
