I know one, which is the precedent of only having two terms. Now it’s a law that Presidents can not serve more than two 4-year terms, but that wasn’t enacted until after FDR served 3 terms during WWII. Washington only served 2 as the first president, so pretty much every president after him was expected to follow his lead.
The second one may be his stance on neutrality. Washington wanted the United States to mostly stay neutral and isolated from European conflicts and urged future presidents/Americans to take the same position.
I’m sure there are others, but those are the two main ones I remember.
