Respuesta1
Una respuesta con una definición de myquote
entorno quote
se define en article
documentclass, pero sin reducir el margen derecho:
\documentclass{article}
\usepackage{blindtext}
\newenvironment{myquote}
{\list{}{}%In this second argument was \rightmargin\leftmargin that is unwanted for you
\item\relax}
{\endlist}
\begin{document}
\blindtext
\begin{quote}
Our first list with three items: % Corrected the ``two'' but not in the photo
\begin{enumerate}
\item test line here that will reach the right margin inside my quotation and will go to the next line
\item test line here that will reach the right margin inside my quotation and will go to the next line
\begin{myquote}
This list contains the next two items:
\begin{enumerate}
\item test line here that will reach the right margin inside my quotation and will go to the next line
\item test line here that will reach the right margin inside my quotation and will go to the next line
\end{enumerate}
\end{myquote}
\item test line here that will reach the right margin inside my quotation and will go to the next line
\end{enumerate}
\end{quote}
\blindtext
\end{document}