\documentclass[a4paper, 12pt]{article}

\begin{document}
\twocolumn

\section{A latex file with two columns}

In this example, the width auto-detection shall detect the two columns
and produce snippets that have the smaller width for a column!

\begin{lilypond}
\score{
  \relative c'{c d e f g a b c | c d e f g a b c | c d e f g a b c}
}
\end{lilypond}

\end{document}