I'm using Spotlight theme, and one of my collections only has a single product, but when i remove the other default blocks in the Collection to only the one, it automatically maximises the image size to full width.
All of my other collections are set to 5 columns so i want to make my collection with the single product the same image size as those.
So just to confirm, on collection pages where there is just one product, you'd like to display the product in the same smaller size that a collection with 5+ products appear?
I've tested this configuration out on the most recent version of Spotlight and I'm seeing that for collections with one product, the image is not larger than on collection pages with 5+ products (see video). Which version of Spotlight are you using?