Any way to set 1 main image on gallery view?

Site URL: https://www.myartbeatflorals.com

So I have a gallery page with "albums" of various weddings and styled shoots I've done. I want only one main image to be seen initially, and ideally I'd like to be able to click into a larger gallery (where you can see all photos) and then click on each image to view it larger (like a lightbox). Currently I'm using the slideshow view without thumbnails...but the images are so tiny and there's no way to see them all at a glance or zoom in. Any coding or hacks that could get me this look? I see photography pages with it all the time. I'm using the Sonny template. TIA!