Instead of showing normal Sitelinks, which are in the screen shot above on the left, you are presented with more detail Sitelinks, which are shown in the screen shot on the right.
How do these new Sitelinks work? When you are shown the new Sitelinks, they are listed under the main search result snippet with arrows down to expand the results. Here is a closer look:
How can I see this in action? I was able to replicate this myself by searching for [translate api] while in Chrome in incognito mode. I was not able to replicate this in any other browser. I was given a heads up on this by SEMRush on Twitter.
Why does this matter? This may change your click-through rates from Google search. If Google shows more of your content directly in the search results, it is possible that people may click less or even more. It is hard to say how the click-through rate from Google search will be impacted by this. It is a similar argument to the featured snippets in search, which is what these new snippets look like. Some studies said the featured snippets resulted in gains, while others showed losses.