%%
%% The LaTeX Companion, 3ed
%%
%% Example A-3-3 on page II-661 in "LR boxes".
%%
%% 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{159.0pt}
%StartShownPreambleCommands
\usepackage{calc}
%StopShownPreambleCommands

\begin{document}
\framebox{ A few words of advice }             \par
\framebox[\width + 8mm][s]{ A few words of advice }
\par  \framebox[1.5\width]{ A few words of advice }
\end{document}