Lightbox 2 gallery

Hello! Sorry if this has been covered, I am not entirely sure what to search for to see if it has already been answered.
I have a question about some layout stuff. ??

Here is my site:
https://www.stillsphotos.dreamhosters.com/test/

Under the portfolio dropdown and into any of the categories, I would like to have posts contain a single image like these:
https://colinbourbon.carbonmade.com/

But, when you click on them, they load up lightbox 2 with a gallery of images.
Is there a way to do this?

Thank you so much!

A newb to wordpress and such…