Japan was the example that stood out to me. (It's where UNIQLO is from.)

I'm 5'11"/180cm with US11/EU45 feet. They didn't sell boots that fit me in Japan. I got a deal on an "XL" jacket that the salesman insisted I buy, because I was the only person to have ever come into the store that it fit. (It's the only thing I've ever worn labelled "XL.")

I'm pretty much the same size as you.

I am a 4XL in China (or was, when I was there last) and a S in the US.

That blows my mind.