Libreoffice Writer / MS word automation

I need to write little information, and get big docx file, based on already provided sentences by the user

Ex: for meetings documents, the user adds the main titles, and the software make a new Docx file, make paragraphs (using sentences provided by the user), includes the titles in these paragraphs

every thing in the software shall be easily edited by the user, because he might need to change font scheme or add paragraphs in the future or anything.

I don't know if you will use Macros or what ever, but it must work with libreoffice on linux and on windows, and preferably on ms word windows

Also
to make things more automated, you may make the solution able to get information from a specific excel sheet/libreoffice Calc and add them to the Docx file automatically.