Hi there,
Does the hover effect (switching from image to content) intentional? Because there is no way you can click an image that’s hidden. Perhaps, what you’re referring is clickable content and open the lightbox? If yes, then please add this to your grid’s custom CSS
.tg-camberra-custom .tg-element-3 {
bottom: 0;
right: 0;
top: 0;
left: 0;
z-index: 999;
width: 100%;
height: 100%;
}
.tg-camberra-custom .tg-element-3 i {
display: none;
}
That should make the lightbox icon cover the entire content and make it clickable, but with that CSS, I hide the icon 
About changing the lightbox’s image size, The grid has no option like that. You should use Essential Grid for that kind of requirement. Example, https://www.themepunch.com/essgrid-doc/lightbox-options/
Thanks!