Just add woff2 font files into your CSS.
Including the following fonts,
-
Source Han Sans CN Regular
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Source Han Sans CN Bold
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Source Han Sans CN Medium
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Source Han Sans CN Light
Other weights can be found in this repo.
https://github.com/adobe-fonts/source-han-sans
https://github.com/google/woff2
No license for this repo. License of Source Han Sans is SIL Open Font.