ENH: PDF Figure Sizes and Harmonise HTML and PDF outputs (automatically if possible)

[mmcky]

Describe the bug

It looks like we may need to figure out a way to harmonise figure/image sizes between html and pdf outputs.

The following pdf file for https://python-programming.quantecon.org/intro.html using jupyterbook-latex for comparisons.

These figures from the website are very small in the pdf file with corresponding myst:

```{figure} /_static/lecture_specific/about_py/python_vs_matlab.png
```

and tex is:

\begin{figure}[htbp]
\centering

\noindent\sphinxincludegraphics{{python_vs_matlab}.png}
\end{figure}

I am surprised by the big difference given there are no scale parameters being used.

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[mmcky]

I think we need to look at either:

1. an automatic scaling factor between html and latex (if possible, to reduce the need for metadata)
2. enable some metadata for scaling images specifically in latex context.