Need help in understanding the '--headless' option more

Hi,
I am using soffice in a headless manner (using
—headless). I am running it on a server that doesn’t have X server and
communicating with soffice using JOD converter.

Generally it hasn’t been a problem, however when I export the
spreadsheet to PDF, wide spreadsheets get truncated and take multiple
pages, which is highly undesirable.

However, when I run the same program on my local dev machine, which
has X server running/display attached, the output PDF gets auto scaled
to a great
extent (very wide spreadsheets still do get truncated).

Can anyone please tell me on what basis does auto scaling happen? What system
parameters are looked at by LibreOffice. If you can point me to set of
files I can look
at to get that answer that will be acceptable too.

I have spent couple of days trying out different options, e.g. using
Xvfb on my server with different screen sizes, but to no avail.

Any help is appreciated.
TIA,

Sunil