Following the documentation for --reference-doc= option available here, if I generate a docx template with:

pandoc -o custom-reference-doc.docx --print-default-data-file reference.docx

The resulting file will show the styles:

But if I create a ODT template with:

pandoc -o custom-reference-doc.odt --print-default-data-file reference.odt

the resulting file only contains "Hello world":

Would it be useful to show the styles also in the ODT template?

Having said that, my understanding is that the contents get ignored in both cases and only the styles are applied.