How to customize the style of font size selector?

I need to change the font size selector text to “一号, 二号, 三号”. How to customize it?
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You can’t, if you’re expecting the numbers to be with Chinese characters and they aren’t, then that is a bug, please report it at the following link: Issues · CollaboraOnline/online · GitHub

While. Thank you! Could I ask which configurations, files, or codes to modify this issue by myself?