%%
%% The LaTeX Companion, 3ed
%%
%% Example A-2-6 on page II-653 in "Defining and changing space parameters".
%%
%% Copyright (C) 2022 Frank Mittelbach
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3c
%% of this license or (at your option) any later version.
%%
%% See https://www.latex-project.org/lppl.txt for details.
%%

\documentclass{tlc3exa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{135.0pt}

  \setlength\parindent{0pt}

%StartShownPreambleCommands
\newlength\Mylen
%StopShownPreambleCommands

\begin{document}
\settowidth \Mylen{Typography} width  = \the\Mylen \\
\settoheight\Mylen{Typography} height = \the\Mylen \\
\settodepth \Mylen{Typography} depth  = \the\Mylen \\
Use larger font and recalculate: \\
\settowidth\Mylen{\large Typography} width = \the\Mylen
\end{document}