The Google Lens feature is being extended to the Galaxy S9, Galaxy S8, and Galaxy Note 8 devices by way of the most recent version of the Google app beta, letting users with any of those three phones get access to the image recognition capabilities through their camera that Pixel and Pixel 2 users have been enjoying for months now. Since this is part of the beta version of the Google app you'll need to have it installed either in place of or in addition to the standard Google app, and to do that you need to become a tester for the app before you can download it.
That's simple enough, though, and upon hitting the button at the bottom you should be asked to become a tester before proceeding. It should also be noted that it isn't verified if you have to be a part of the Google app beta, but it is a possibility so you may want to enroll in it just to be safe and save yourself another step later on if you do need it. Though the Galaxy S9 Plus and Galaxy S8 Plus aren't specifically mentioned they will also have access to the Google Lens features of the beta, so you shouldn't be left out if you opted for the bigger screen versions of either Galaxy S phone.
Phones like the Galaxy S9 and others getting access to Google Lens isn't or at least shouldn't be much of a surprise as Google announced back at the end of February just before Mobile World Congress 2018 started that third-party phones would be getting this capability, at the time though it just wasn't mentioned when the access would start hitting phones. This newly gained access also follows up Google rolling out Lens to all Google Photos users across Android which started more recently. Google Lens is a fairly useful feature for a number of different reasons, but it's extremely useful if you find yourself in situations often where you want to get more information about something, such as landmarks. You simply point the camera at the landmark, or search for it in the Google app, and then tap the Lens button to get more information.