For questions regarding the {adjustwidth} environment from the {changepage} package.

The adjustwidth environment from the changepage package can be used to locally change the left and right margins of a document. The environment takes two mandatory arguments that can be either positive (increase respective margin) or negative (decrease respective margin).

\begin{adjustwidth}{<change to left margin>}{<change to right margin>}

The starred variant adjustwidth* is useful for twosided documents and alternates the values of the margins between odd and even pages.

\begin{adjustwidth*}{<change to inner margin>}{<change to outer margin>}

The adjustwidth environment can also be used inside of a floating environment such as figure or table.


\documentclass{article}
\usepackage{lipsum}
\usepackage{changepage}

\begin{document}
\lipsum[4]

\begin{adjustwidth}{1cm}{1cm}
\lipsum[4]
\end{adjustwidth}

\lipsum[4]

\begin{figure}[htbp]
\begin{adjustwidth}{-0.125\textwidth}{-0.125\textwidth}
\rule{1.25\textwidth}{1cm}
\end{adjustwidth}
\end{figure}

\lipsum[4]
\end{document}

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