Is there a world ETF that excludes US? Does it make sense to buy world ETF (including US) + S&P 500, or world ETF (excluding US) + S&P 500? Why?

As a more separated approach

you could install your own free mix of the economically best countries via country index ETFs

U.S. (SP500)

China

Sweden, Denmark, Norway

Switzerland

Singapore

Germany

Japan

Canada

World ETF contains everything in the S&P 500. When you buy a world ETF, you are simply buying the entire array of stocks out there (the good/meh/bad). I would say you can use the World ETF as a base (core) and then add on some sector specific ETFs to capture higher gains or even better, go for high growth ETFs such as ARK which I think too many people overlooked because its an absolute GEM.