LaTeX的section章节标题怎么设置为1,2,3？现在显示不了

aTeX的section章节标题怎么设置为1,2,3？
\usepackage{titlesec}
\titleformat{\section}{\Large\bfseries}
\titleformat{\subsection}{\large\bfseries}
\renewcommand\thesection{\arabic{section}}

\begin{document}
\section{Title 1}
\section{Title 2}
\section{Title 3}