Provide examples on how to write multiple non-Latin scripts / non-English languages in the latex template

[laubonghaudoi]

I need to write Arabic, Chinese, Cyrillic and Greek in the same .tex document, and I am having a very difficult time to set up the environment. Because the your latex template limits the compiler to pdfLatex, and

\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}

I still haven't found a way to successfully compile the .tex file with these 4 scripts. Examples in https://www.overleaf.com/learn/latex/Multilingual_typesetting_on_Overleaf_using_babel_and_fontspec didn't work for me and I had numerous compiling errors. I would really appreciate if someone can provide an example how to do this in the latex template.