On a Comment of Percusse: "Shrink Paper Size, Print Big!"

Question

In the post Should I use \documentclass[12pt]{article} with \Large or \documentclass{article} with \LARGE?,

Percusse made the following comment:

PDF is vector. Shrink paper size, print big!

QUESTION: Does this mean that if one geometrically reduces the paper size from say paperwidth=5in and paperheight=8in to, say, paperwidth=4in and paperheight=6in, \footnotesize will actually appear larger in the latter than it would in the former?

I ask, because I have been working on a 4'' x 6'' book, in which footnotesize, in no way, appears to be too small; whereas, I suspect it would be far too small if the book were geometrically larger.

Are my eyes, perhaps, playing tricks on me? I have printed a couple of page sized by side an a landscape 8 1/2'' x 11'' piece of paper and the footnote fontsize seems fine to me---but I could very well be wrong.

For what it's worth, I have put together the following MWE which sets the default font size at 10pt and prints a few sentences with the default, with normalsize (which seems to be the deafault), and footnotesize (with a footnote)---the font sizes of which appear (roughly) to be the same.

\documentclass[titlepage,10pt]{book}
\usepackage[showframe,margin=.3in,paperwidth=4in,paperheight=6in]{geometry}

\textheight=5.25in 
\hoffset 10pt
\topmargin -65pt
\headheight 15pt 
\headsep 10pt 
\marginparwidth 35pt


\begin{document}
\thispagestyle{empty}

This is a sentence. (default (10pt)) \\[15pt]

\normalsize
This is a sentence. (normalsize) \\[15pt]

\footnotesize
This is a sentence. (footnotesize)\footnote{This is a footnote.}
\end{document}

which produces

Thank you.

Answer 1

Note as percusse commented later the first comment was intended mostly as a joke, but anyway if you are using fonts with optical scaling specifying a font that is twice the size is not the same as scaling the document later. One uses a 20pt font designed for headings one uses a 10pt font designed for text, enlarged. Either have their uses, it depends what the use is.

If you want a large-print book for children or accssibility or whatever, rather than use \large everywhere you can design for A6 and print (scaled x 2) on A4, or for US paper design for 5" but print on 10" that was I believe the context of the old question asking about \large, But if you are designing on 5" to print unscaled at 5" then naturally you get the size you specify.