The Apple Watch Series or later can display heart rate during workouts. If you are not getting HR on your watch, check the Privacy settings on you iPhone. Open the Settings app, and go to Privacy Settings > Health > Stryd. Make sure the settings allow Stryd to access the health data (screenshots below).
Next, make sure the Apple watch is not using Workout Power Saving mode (which will disable HR recording). Open the Watch app on your iPhone. Select General settings, look for Workout Power Saving mode. Make sure it is disabled.
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