Adjust page length in a long piece

Scrivener compile turns out a nice PDF for publication (in my case, trade paperback), yet there are specific adjustments I’d like to make to push or pull the text a bit. As in the attached, where the *** I use for a section break appear at the very top of a page. Should I just adjust margins a titch, or is there a page-by-page way to adjust?

Out of interest, why do you want to change this? It is standard for such breaks to appear at the top or bottom of a page in a book to show that there is a break, otherwise the reader has no way to tell that there is an intended break between pages.

All the best,
Keith