Not really, Google only indexes what’s on the page, not what’s powering it.
Searching for “proudly powered by wordpress” will reveal most of the sites which haven’t gone to the trouble of editing their footer credits.
That search reveals 40,600,000 results in Google. If that number seems high, it’s because WordPress currently powers 26.4% of the known web, so actually it’s a bit low: https://w3techs.com/technologies/history_overview/content_management/all/y
Also, have a look at these lists:
Home
https://vip.wordpress.com/clients/
https://w3techs.com/technologies/details/cm-wordpress/all/all
