how can I access a paragraph object in writer?

[JimOKC]

Where can I find documentation of the various object models?

[Hrbrgr]

There is the documentation of LibreOffice:

https://documentation.libreoffice.org/en/english-documentation/

And about style templates for paragraphs and headings:

Style template in Writer - LibreOffice 5.3

If you have detailed questions, feel free to contact. You can edit your question or leave a comment.