Not but given that his public interactions like re-tweeting blurbs about "The only good democrat is a dead democrat"[1] i would argue America's internal discourse has gotten far, far worse as a direct result of his behavior.
[1]: Yes, he retweeted this. The video blurb does not give any more context. The full video does, as they only call for death of Democrats "politically speaking", but not only is this retweet from the President a great example of how violent blurbs without context are unconstructive, we've seen example of violent acts recently that one can't help but feel the President personally promoted - for example the attempted kidnapping of a democrat official. Context is king, and the President is known for giving vague and awful statements without context. For his followers that only look skin deep, of which plenty of humans do, what do you think they take from this?
US foreign policy was affected, though not by his tweets. Dipping out of the Paris Agreement, starting a trade war with China, cozying up with Russia which has a chilling effect with historical allies, almost starting a war with Iran right before the pandemic hit its stride
