Google is testing a larger sized font for the URL in Google’s search results.  The new size being tested is actually larger than the description beneath it.  It is closer in size to the search results title.

Here is how it appears in the search results.  The top result is the larger URL while the second is the regular version Google usually serves to searchers.

This test does make the URL stand out more than the smaller regular version.  But it is hard to know if it would have any impact on CTR, although some searchers do look for specific domains when searching.

This seems to be a limited test as I could not replicate it.  However, Google is often testing various things in the search results, so this is likely just another one of those tiny tests.

Thank you to Frank Sandtmann for sending the screenshots to TheSEMPost.  Here are the full screenshots:

And here is how it normally looks.