I am trying to create documents with emojis and words of non-English alphabet (Farsi, Chinese, Korean etc), but I heard that plain TeX does not support this, but plain XeTeX does offer support. However, when I type in these characters, the output PDF is blank, so I don't know if I am missing a package or something else. Can someone give a Hello World demo?
P.S. I am only interested in using Plain XeTeX or Plain TeX (if there's some supporting package).