Google Lens is activated within the Google Photos app and a user on Reddit found that the button had magically appeared on his Pixel XL‘s app without any Play Store update. That means that the functionality and unlocking of such functionality is handled server side by Google, so can appear and disappear at any time.
Note the “Pixel preview” text below the Google Lens icon. While many people seem to be reporting the Lens functionality has appeared, there is also just as many reporting that it isn’t appearing in their Photo app.
Google Lens used AI to pull information about a photo and present relevant information linked to that image. It’s similar to how Google Googles used to work but it’s good to see the functionality extended beyond the latest Pixel devices. Hopefully it will make an appearance to other Android devices in the near future.