The ODT export back-end comes with many OpenDocument styles (see Working with OpenDocument style files). To expand or further customize these built-in style sheets, either edit the style sheets directly or generate them using an application such as LibreOffice. The example here shows creating a style using LibreOffice.
#+OPTIONS: H:10 num:t
org-odt-styles-fileand point it to the newly created file. For additional configuration options, see Overriding factory styles.
To apply an ODT style to a particular file, use the ‘ODT_STYLES_FILE’ keyword as shown in the example below:
#+ODT_STYLES_FILE: ("/path/to/file.ott" ("styles.xml" "image/hdr.png"))
The ODT export back-end relies on many templates and style names. Using third-party styles and templates can lead to mismatches. Templates derived from built in ODT templates and styles seem to have fewer problems.