Tikz - Can't increase font size in node

Question

MWE:

\documentclass[]{article}
\usepackage{fancyhdr}
\usepackage{enumitem}
\usepackage{amsmath}
\usepackage{color}
\usepackage[left=1.5in,right=1.5in,top=1in,bottom=1in,
footskip=0in]{geometry}
\usepackage{tikz}

\begin{document}

    \begin{tikzpicture}[scale=1.25]
    \draw[fill,yellow] (0,0) circle [radius=1];
    \draw (0,0) circle [radius=1];
    \node at (0.03,0) {\textrm{\textbf{\Huge ER}}};
    \end{tikzpicture}

\end{document}

When I change the font size in the node from \Huge to \LARGE, for instance, I can see the difference.

Now, in line with some other answers I've seen on the site, I tried:

\node at (0.03,0) {\textrm{\textbf{\fontsize{100}{0}\selectfont ER}}};

But I can't seem to get the font size to increase no matter how large a number I choose, e.g. 150, 200, etc.

Any ideas why?

Answer 1

this is unrelated to tikz, latex warns

LaTeX Font Warning: Size substitutions with differences
(Font)              up to 75.12pt have occurred.

You see the same from

\documentclass[]{article}


\begin{document}
\fontsize{100}{0}\selectfont ER

\end{document}

The default cm fonts are only enabled at a fixed set of sizes, if you add

\RequirePackage{fix-cm}

at the top of the file then they will be allowed to scale to arbitrary size, or switch to lmodern which uses scalable font sizes by default.