[Tex/LaTex] Specifying percent of font size (as normalsize)

fontsize

I'm trying to replicate the format/style of a document, and I got somewhat stuck at specifying font size, which it turns out, isn't all that easy (if you want to keep \normalsize, \large etc for font sizes different from 10, 11, or 12 – or if you mess with margins):

For me, the problem is that it seems I need to have the Palatino font between sizes 8pt and 9pt; but since specific files are being loaded (and lineskips calculated) from specific files related to these sizes (e.g. latex/extsizes/size8.clo), I can't just put in "8.5pt". Here's my example so far: 

\documentclass[8pt]{extarticle}

\usepackage{geometry}

% specify new page size - ripped from geometry package:
\makeatletter
\@namedef{Gm@envelope6x9paper}#1{\Gm@setsize{#1}(6,9){in}}%
% % ‘paper' = paper takes a paper name as its value.
\define@key{Gm}{paper}{\setkeys{Gm}{#1}}%
\let\KV@Gm@papername\KV@Gm@paper
% The following paper names are available.
\define@key{Gm}{envelope6x9paper}[true]{\Gm@setpaper@ifpre{envelope6x9paper}}%
\makeatother

\geometry{envelope6x9paper, inner=0.6in, outer=1in, twoside=true, top=1in, bottom=1in}

\usepackage{mathpazo} % palatino; no [scaled=0.92]
\usepackage{lipsum}

\usepackage{titlesec}
\titleformat{\section}{\large\bfseries}{\thesection}{1em}{}
\titlespacing{\section}{0pt}{\baselineskip}{*0}

\title{My New Document Class Test}
\author{Testus}

\begin{document}

% to match comparison PDF:
% increase page counter once, so we start on even page (that would be open left, presumably)
\stepcounter{page}

\maketitle% Actually makes a title page

\section{Intro}
\lipsum[1-4]

\section{More stuff}
\lipsum[5-9]

\end{document}

I was thinking – if I could "scale" the "default" font size; presumably that would "propagate" to all the line spacings too; but unfortunately, mathpazo doesn't have a [scaled] option (like helvet, I guess).

So is there a LaTeX way (for the time being, I'd like to avoid switching to KOMA-Script), so that the above example can be modified in the preamble, such that the normal size of the used font becomes 150% bigger than the originally loaded font (with which, I expect, I would get approximately something like 8.5 pt – if I load 8pt)?

EDIT: Just found Continuously-sizable fonts?, and tried to use scalefnt:

\usepackage{scalefnt}
\scalefont{1.5}

… but it seems to have no effect above…

Best Answer

Ok, I think I found a rather good explanation here: LaTeX Community • View topic - Font Sizes:

size10.clo defines
\newcommand\Huge{\@setfontsize\Huge\@xxvpt{30}}
The macro \@xxvpt, which looks like roman representation of arabic 25pt, is defined in latex.ltx:
\def\@xxvpt{24.88}
Similar for the other values.

... and so, if one checks the size8.clo - it similarly defines all of the parameters, more or less, explicitly - instead of relatively (which the original post assumes).

So probably the plain Latex way would be to copy the size8.clo into a new file, and then change all parameters there (and then load the new size / changed file)... but that's gonna be some work :)

If anyone's got anything easier, please post :)

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