[Tex/LaTex] How to change section/subsection font size?

fontsizesectioningtitlesec

I'm writing a paper that requires the section titles to be in 12pt font, I can get the title to be in 12pt using:

\section{\fontsize{12}{15}\selectfont Introduction}


but the section number does not change size, is there a way to do this?

I've also tried looking at titlesec but have not been able to find any suitable examples.

Here's one possibility using the sectsty package:

\documentclass{article}
\usepackage{sectsty}

\sectionfont{\fontsize{12}{15}\selectfont}

\begin{document}

\section{Test Section}
test

\end{document}


The titlesec package could also be used:

\documentclass{article}
\usepackage{titlesec}

\titleformat{\section}
{\normalfont\fontsize{12}{15}\bfseries}{\thesection}{1em}{}

\begin{document}

\section{Test Section}
test

\end{document}