Donald Trump tweeted on August 19, 2019
Wow, Report Just Out! Google manipulated from 2.6 million to 16 million votes for Hillary Clinton in 2016 Election! This was put out by a Clinton supporter, not a Trump Supporter! Google should be sued. My victory was even bigger than thought!
The Hill explains the context of the tweet:
Trump appears to be referring to the work of Robert Epstein, a researcher with a group based in Vista, Calif., called the American Institute for Behavioral Research and Technology. Epstein testified in a Senate hearing in June about what he calls the "Search Engine Manipulation Effect" and claimed that his research shows Google's search results pushed at least 2.6 million people to vote for Clinton in 2016.
The Hill goes on to quote Google's CEO as denying it.
Did Google manipulate its search engine results to push many millions of voters towards Clinton?