Hello Pratik Vyas, I think you can implement it on the device or use a web service. It all depends on your purposes.

If you are going to implement it on the device, I would suggest searching for some face recognition or computer vision library. You can also implement it from scratch using Java or Kotlin.

Otherwise, if you intend to use a web service you can implement it by your self, using, for example, Python and OpenCV, or even using this Go implementation, and use it as a service, or search for some face recognition web service. Here are some examples:
https://aws.amazon.com/pt/rekognition/
https://www.hackster.io/tabvn/python-face-recognition-web-service-9f0aa5