I don’t know. I think that’s a more complicated question.
Could our joining the League of Nations prevented the rise of Hitler and the rise of Imperial Japan?
I seriously doubt it.
Anyway, that’s kind of ancient history now. Set in stone.
Although our current membership in the UN is probably very secure, I wouldn’t say it’s set in stone.
It is conceivable that we quit the UN and kick them out of the US. Highly unlikely, but conceivable.
It is not conceivable that we go back and change the history of post WWI United States.
Unless we develop FTL, which implies time travel. But if that’s possible, then where are the time travelers from the future? Should we be seeing them now?
IMHO the US should stay in the UN organization but the location of the UN building should change.
The new facility should be integrated into a remote section of our Southern Border Wall. Money we’ve budgeted for UN money could be used for the construction as well as the money made from selling the current real estate.
Think of the many benefits, including less congestion in NYC.