Hello vibhas114,
Let's start off by checking the helpful steps in this article which can help with this issue, even if the issue is only intermittent: If Face ID isn't working on your iPhone or iPad Pro.
Please also keep this information in mind:
"You might need to enter your passcode or Apple ID instead of using Face ID in these situations:
- You're wearing a face mask and haven't set up Face ID with a mask.
- The device has just been turned on or restarted.
- The device hasn’t been unlocked for more than 48 hours.
- The passcode hasn’t been used to unlock the device in the last six and a half days and Face ID hasn't unlocked the device in the last 4 hours.
- The device has received a remote lock command.
- After five unsuccessful attempts to match a face.
- After initiating power off/Emergency SOS by pressing and holding either volume button and the side button simultaneously for 2 seconds."
Let us know if we can help with anything else at all or if this doesn't settle your issue so we can look into this further with you. Thanks and have a fabulous day!
