Hi
It is not possible to adjust the intensity of the sensors on Apple Watch.
If you experience redness, swelling, itchiness, or any other irritation or discomfort on your skin around or beneath your watch, Apple recommends that you remove your watch and consult a doctor / physician before wearing it again.
Discomfort or skin reactions can be a result of various causes including:
- Allergies (eg to nickel);
- Extended exposure to irritants (eg soap or sweat);
- Environmental factors;
- Wearing the band too tightly or too loosely.
More information:
Wearing Apple Watch - Apple Support
Cleaning and wearing Apple Watch - Apple Support