%%
%% The LaTeX Companion, 3ed
%%
%% Example 2-2-14 on page I-45 in "The extended interface".
%%
%% 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{titlesec}
\titleformat{\section}[frame]{\normalfont}
    {\footnotesize \enspace SECTION \thesection
     \enspace}{6pt}{\large\bfseries\filcenter}
\titlespacing*{\section}{1pc}{*4}{*2.3}[1pc]
%StopShownPreambleCommands

\begin{document}
\noindent \ldots some text before \ldots
\section{A Title Test}
Some text to prove that this paragraph is not indented
and that the title has a margin of 1pc on either side.
\end{document}