The latest update to Google Photos Android and iOS apps brings the ability to edit your media’s time and date directly within the app. Once in the Google Photos mobile app, you can now swipe up on any image or video and you should have a marker in the right corner which means you are able to tinker with the date and time.
The feature was already available on the web version of Google Photos for quite some time. If you did not have access to a desktop before and wanted to change the date and/or time of a photo on Google Photos via your phone or tablet, you’d have to resort to third-party apps. If you are still not seeing this change on your device, you should make sure your app is updated to the latest version.