Using custom code to get different ratios of store product images

I'm relatively new to square space and slowly building my site with a view to sell photography prints. 

I've got 2 images listed as purchasable prints so far, but I',m having an issue with the aspect ratios of the product images. 

One picture is in the landscape orientation, 3:2 aspect ratio, and the other should be in portrait orientation, 2:3 aspect ratio.

However, whenever I change the aspect ratio of one product image, that change is made across both products. 

After talking to Square Space live chat, I was told the solution is to use a custom code. 

This is where I'm lost as I have no experience with custom code and don't know where to begin. 

Any insight would be appreciated. 

Do you mean in the gallery or in product cards on the shop page? Please provide a link to the site.

Thanks for your reply. 

It's the product image on the shop page, called Prints on my site

This is the page with the specific issue. I want this product image to be in the ratios 3:2 https://www.richardpowellphotography.co.uk/prints/p/ohio-pass

That's great, thank you. I'll add it and see how I get on