New iPhones have super fast custom CPU, so it can do local image processing.
With help of "cloud" any web site of app could do similar. Amazon Rekognition – Deep learning-based image analysis"Amazon Rekognition is a service that makes it easy to add image analysis to your applications. With Rekognition, you can detect objects, scenes, faces; recognize celebrities; and identify inappropriate content in images. You can also search and compare faces. Rekognition’s API enables you to quickly add sophisticated deep learning-based visual search and image classification to your applications."Face API - Facial Recognition | Microsoft Azure"Detect human faces and compare similar ones
Organize images into groups based on similarity
Identify previously tagged people in images"