Compile with PDFLaTeX
If you choose PDFLaTeX to process your paper, the default article font computer modern has changed to newtx series, and the default font size is set to 11pt . The fonts are settings with:
newtxtext package for text fonts, similar to times new roman font.
newtxmath package for math fonts, close to times package.
FiraMono package for typewriter fonts, with option scale=0.8 .
ctex package for Chinese fonts, with option scheme=plain .
Compile with XeLaTeX
If you choose XeLaTeX to process your paper, I use fontspec package and xeCJK package. I used fonts available in Windows, if you are using Linux or Mac OS, please substitute these fonts with that of your system. The font setting part
Other Settings
These packages operate perfectly but are inappropriate for big operators, for example \sum and \prod, thus, I change these operators back to computer modern font.
The \linespread (controls line spacing) is set to 1.3, and I use microtype to improve the font justification. type1cm package is used to remove the font shape and font size warning messages.