Turn vibration off for all alarms
1. Go to Settings > Sound & vibration.
2.
Tap Vibration & haptics and check that Use vibration & haptics is on  .
3.
Under Notifications and alarms, turn Alarm vibration off  .
This overrides the vibration setting for individual alarms.
If you don't feel vibration and expect to
1. Go to Settings > Sound & vibration.
2.
Tap Vibration & haptics and check that Use vibration & haptics is on  .
3.
Under Notifications and alarms, turn Alarm vibration on  .
Settings : Sound & vibration 208