Envira’s Fullscreen Addon will allow you to set up your lightbox to either open the lightbox in Fullscreen or allow the user to go full screen with the click of a button.
Gallery configurations:
3 columns with lazy loading. Supersize, Deeplinking, Fullscreen and Fullscreen when the lightbox opens. Sleek lightbox theme. 1024×1024 image size with no cropping. Lightbox transition on open and close is set to Fade and Lightbox transition for navigation set to Slide.