I am trying to get from HTML originally intended for Kindle formats, to an output appropriate to KDP paperback format.
Calibre appears to be producing 8 1/2 x 11" output, too large for this service to accept. A little searching has a Library of Babel tinge to the documentation. Doing a "ebook-convert" by itself has three options, one of which looks promising but "ebook-convert --recipes" does not do a standard "List all, or all major, options"
Let's say that I have material in HTML, ePub, or .mobi.
How can I convert this to a PDF file of my own, with a page size of 6x9"?