答案1
\documentclass{scrartcl}
\usepackage{scrlayer-scrpage}
\pagestyle{scrheadings}
\ohead{left}
\ihead{right}
\usepackage{lipsum}
\begin{document}
\section{some section}
\lipsum[1-3]
\newpage
\pdfpagewidth= 2\paperwidth
\begin{addmargin}[0pt]{-\paperwidth}
\lipsum[1-3]
\end{addmargin}
\lipsum[1-3]
\newpage
\pdfpagewidth= \paperwidth
\lipsum[1-3]
\end{document}
\tableofcontents
\setcounter{chapter}{88}
\chapter{Chapter 89}
0123456789
\section{Section 89}
\subsection{Subsection}
\end{document}