Code or Extension to achieve custom lightbox pop-up?

I am building a site for a client who has asked for lightbox functionality on clicking on a gallery image.

I have created a block with 3 x Gallery images (see attached). Each image has the title/ description displayed below. The client would like to be able to click an image to open a lightbox or overlay where we can have additional content on each tour (ie. Beach Run). Additional content would be, for example, header, paragraph text, image, bulletpoint list, etc.

I am interested in understanding the best way to achieve this as the client doesn't want to open up a page in a new tab to take customers away from the original tour page.

Is this something that can be done with native Squarespace functionality (I don't think so)? Or an extension/ plug in? Or would it be custom code?

Any help gratefully received. 

You can use a Lightbox Plugin (affiliate link) or this link (non-affiliate link) to achieve this

I created a quick demo for you here: https://tuanphan.squarespace.com/hover-text-show-lightbox-1?noredirect (use Image Block)

or https://tuanphan.squarespace.com/gallery-page-with-lightbox-1?noredirect (use Gallery Section)

password: abc

You can enable Lightbox appears by Hover or Click.

You can use Lightbox with any blocks (Gallery Block, Gallery Section, Carousel, Text Block, Image Block, Video Block, Code Block, Button Blocks, Navigation Items, Header Buttons..)