Custom margin settings for figure in LaTeX

\centerline{\includegraphics{...}}

Does this without any hspace trickery.

If the figure is e.g. 3 inches too wide, add a negative space of half that before the figure:

\hspace*{-1.5in}
\includegraphics{...}

The above did not work for me as I wanted the figure wider than the caption. Also, I think there is a override by the endfloat package.

This will leave the entire document intact and only alter the figure:

\begin{figure}
    \advance\leftskip-4cm
    \includegraphics[options]{location}
\end{figure}

You could also use:

\advance\rightskip-2cm