How to actually change font size in beamer presentation?

[icarosadero]

Description

I am using a jupyter notebook to generate a beamer presentation via quarto, this thread says that I just have to add fontsize: "5pt". So, this is what I did in a markdown cell right at the beginning of the notebook:

---
title: "Test"
format:
    beamer:
        theme: metropolis
        fontsize: "5pt"
        pdf-engine: pdflatex
keep-tex: true
---

Except that when I run quarto preview notebook.ipynb --log quarto.log, the size doesn't change regardless of the value I put on the font size argument.

Inspecting the tex file that is generated, it does include the right font size in the preamble

\documentclass[
  5pt,
  ignorenonframetext,
]{beamer}

.

So, I don't understand why it doesn't actually change.

[cderv]

See explanation at

• Changing font size in Beamer presentation? #5025

Beamer does seem to support only a set of fontsize.