[Quoth]

But edit in odt and an extra Save As in docx for Calibre.
All the paragraph and heading styles perfectly 1:1 as CSS after conversion to epub2.
You might need to edit CSS of images.
Make any other ebook format from the epub2

I don't use any of the default LO Writer styles, but define my own headings with Page Break Before and a Headling Level.
I defined other styles for:
1 regular paragraph,
2 first paragraph after any centred element.
3 Preamble titles
4 Preambles
5 captions
6 quotations
7 letters
8 old typewriter notes or console text
9 list headings
10 list elements and they never have auto number/letter or bullets. Explicitly type those in at start of each list element for 100% compatibility.
11 Notes in a rectangle box (even works converted to old mobi).

Undock the Style browser (set to Paragraph) and Outline/Navigation/Heading browsers.

Leave page style undefined in Insert Page break except for version to export as PDF. Only edit a copy for PDF export if needed when version for epub is polished.
Never edit the "Save As" docx, only odt.