These are different than the sitelink sub-listings that have been around for a while. I was searching for “business with multiple locations one website or different website” and the search results showed me Search Engine Journal – one result with the “main” content and a sub-listing with a related piece of content. I don’t remember seeing this layout before, is this relatively new?
I wish I could link to a screenshot I took, but unfortunately this sub doesn’t allow images. If you search that same term I imagine the results will be the same.