Change size of section, subsection, subsubsection, paragraph and subparagraph title

Question

I would like to increase the size of pretty much every headlines, so that it is more prominent than the normal text.

I read about the titlesec package, but can't seem to find good example how to use the package.

Using Gonzalo Medina does in fact change the font size, however, it changes the default font as well.

Before:

After:

Answer 1

Here's an exaple using titlesec:

\documentclass{article}
\usepackage{titlesec}

\titleformat*{\section}{\LARGE\bfseries}
\titleformat*{\subsection}{\Large\bfseries}
\titleformat*{\subsubsection}{\large\bfseries}
\titleformat*{\paragraph}{\large\bfseries}
\titleformat*{\subparagraph}{\large\bfseries}

\begin{document}

\section{Test section}
\subsection{Test section}
\subsubsection{Test section}
\paragraph{Test section}
\subparagraph{Test section}

\end{document}

I used the simplified version of \titleformat (i.e., \titleformat*) since the only desired change was in size, but you can use the extended version if "bigger" changes are required. These are the default definitions for the standard classes (taken from the documentation):

\titleformat{\section}
{\normalfont\Large\bfseries}{\thesection}{1em}{}
\titleformat{\subsection}
{\normalfont\large\bfseries}{\thesubsection}{1em}{}
\titleformat{\subsubsection}
{\normalfont\normalsize\bfseries}{\thesubsubsection}{1em}{}
\titleformat{\paragraph}[runin]
{\normalfont\normalsize\bfseries}{\theparagraph}{1em}{}
\titleformat{\subparagraph}[runin]
{\normalfont\normalsize\bfseries}{\thesubparagraph}{1em}{}

so you can make bigger changes. The following image shows both the standard sizes and the ones obtained with the above modifications:

And here's an exampe using the sectsty:

\documentclass{article}
\usepackage{sectsty}

\sectionfont{\LARGE}
\subsectionfont{\Large}
\subsubsectionfont{\large}
\paragraphfont{\large}

\begin{document}

\section{Test section}
\subsection{Test section}
\subsubsection{Test section}
\paragraph{Test section}
\subparagraph{Test section}

\end{document}

According to an edit to the original question, the OP wanted also a sans serif font:

\documentclass{article}
\usepackage{titlesec}

\titleformat*{\section}{\LARGE\bfseries\sffamily}
\titleformat*{\subsection}{\Large\bfseries\sffamily}
\titleformat*{\subsubsection}{\large\bfseries\sffamily}
\titleformat*{\paragraph}{\large\bfseries\sffamily}
\titleformat*{\subparagraph}{\large\bfseries\sffamily}

\begin{document}

\section{Test section}
\subsection{Test section}
\subsubsection{Test section}
\paragraph{Test section}
\subparagraph{Test section}

\end{document}

The above approaches are to be used mostly with the default document classes (book, report, article); if the document class used is one of the classes of the KOMA-Script bundle, then it's not advisable to use titlesec (See About KOMA-Script and titlesec incompatibility) but to use the features provided by the KOMA classes:

\documentclass{scrartcl}

\setkomafont{section}{\LARGE}
\setkomafont{subsection}{\Large}
\setkomafont{subsubsection}{\large}
\setkomafont{paragraph}{\large}
\setkomafont{subparagraph}{\large}

\begin{document}

\section{Test section}
\subsection{Test section}
\subsubsection{Test section}
\paragraph{Test section}
\subparagraph{Test section}

\end{document}

For the memoir document class, the situation is analogous: is also not advisable to use titlesec (See About memoir and titlesec incompatibility) but to use the features provided by the class; if I have the time I'll add some example.

Answer 2

You can just modify the sectional commands with the appropriate font size. Here's a small example in the article document class:

\documentclass{article}
\begin{document}
\section{A section}
\subsection{A subsection}
\subsubsection{A subsubsection}

\makeatletter
\renewcommand\section{\@startsection {section}{1}{\z@}%
                                   {-3.5ex \@plus -1ex \@minus -.2ex}%
                                   {2.3ex \@plus.2ex}%
                                   {\normalfont\LARGE\bfseries}}% from \Large
\renewcommand\subsection{\@startsection{subsection}{2}{\z@}%
                                     {-3.25ex\@plus -1ex \@minus -.2ex}%
                                     {1.5ex \@plus .2ex}%
                                     {\normalfont\Large\bfseries}}% from \large
\renewcommand\subsubsection{\@startsection{subsubsection}{3}{\z@}%
                                     {-3.25ex\@plus -1ex \@minus -.2ex}%
                                     {1.5ex \@plus .2ex}%
                                     {\normalfont\large\bfseries}}% from \normalsize
\makeatother

\section{A section}
\subsection{A subsection}
\subsubsection{A subsubsection}

\end{document}

For a different font, replace \normalfont with the appropriate definition. For example, using \sffamily will yield:

Answer 3

For completeness I'll give a ConTeXt solution also.

You can change the heading style using:

\setuphead[chapter,title]        [style=\tfd]
\setuphead[section,subject]      [style=\tfc]
\setuphead[subsection,subsubject][style=\tfb]

The font switch \tf equals the body fontsize, \tfa is 1.2 times \tf; \tfb is 1.2 times \tfa and so on. If you want sans serif headings, then use

\setuphead[chapter,title]        [style=\ssd]
\setuphead[section,subject]      [style=\ssc]
\setuphead[subsection,subsubject][style=\ssb]

Here also the same logic applies. \ss is sans serif at body fontsize; \ssa is 1.2 times \ss, \ssb is 1.2 times \ssa, and so on.