How to format font size, font type in all new documents

how to setup (for all new documents) the type and size of font

The answer is the same as for this question.

A template may contain all your favorite parameters: paragraph styles (defining font properties), page styles (margins, paper size), and also default initial content.

In case you only want to set font face and size, go to Tools>Options, LibreOffice Writer>Basic Fonts(Western).

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