Can you explain in more detail? The sensors are automatic, you just have to make adjustments on whether you want continuous or periodic measurements. And it can't be done without a connected watch. Your phone, by itself, cannot measure your heart rate or stress level--it's the watch that has those sensors.
The phones haven't had this capability for several years. The solution is to get a Samsung watch. The watch has this ability and will report the info to Samsung Health on your phone.
