If you’ve got the latest feature update to Windows 11, you’ll notice some improvements in the Photos App.
One of the neat, new features is the ability to view selected images side-by-side. To check it out, just select a photo in your files and click to open. You’ll see this screen with thumbnails of other images displayed at the bottom.
To view another image side-by-side with the current one, just single-click on it.
They will display side-by-side.