How to config excel date format when using soffice convert-to html?

Fail to find ways to config date format when using soffice convert-to util.

As default, it returns as US like 9/7/2018. For Chinese, it’s hard to determine July 9th or Sept 7th.
It works when changing the Locale setting in preference via GUI, and then exports as 2018年9月7日.

Is there any way to change the date format without configuring via GUI?

No (at least when using --convert-to). Cell format is defined in the document; and --convert-to doesn’t change document content; it only tries its best to translate the existing content from one document format to another.

EDIT:
if LibreOffice locale affects the format, then it means that cells use “default” format; in that case, if you have set correct locale, --convert-to should do its job for you.

I think the document doesn’t matters. The same document opened with different Locale setting shows different date format. Also, the Date acceptance patterns changes with the Locale settings.

As I said - then simply setting the locale should work. What is the problem here?

Yeah, it does.