The only attributes Google would recognize and do anything with are the supported link attributes, such as rel=nofollow, rel=sponsored, and rel=ugc. But rel=dofollow means nothing to Google, Google will just crawl it like the rel link attribute is not even there. Occasionally I stick funny things in my link attributes just to see if anyone would pick up on it, no one does.

Just in case it wasn't clear from all the replies here, using an unknown rel-attribute on links doesn't do anything, and since the default behavior is to use links normally, this just treats links like links. You don't need to use rel=dofollow. You can, but you don't need to.
— johnmu