Jetpack Tiled Galleries lets you display your image galleries in three new styles: a rectangular mosaic, a square mosaic, and a circular grid.
To enable this feature, go to: Jetpack Settings > Appearance and turn on Tiled Galleries. There is one feature, which converts existing galleries into Jetpack Tiled Galleries.
With this feature enabled, you can now create a photo gallery like normal, but when it comes to the final gallery creation screen, you can choose from the new “Type” option.
You’ll want to experiment with the different gallery types to see which one looks the best for your site.