98%+ of all Google+ public content was archived and was / will be posted to the Internet Archive.

https://www.archiveteam.org/index.php?title=Google%2B

You'll need to know, or track down, the user or content page to find it. E.g.

https://web.archive.org/web/20190102053619/https://plus.goog...

Raw archive dumps:

https://archive.org/details/archiveteam_googleplus