\input{umtest-preamble}
\usepackage{unicode-math}
\setmathfont{Cambria Math}
\begin{document}
\[ \left‖ \left‖ \left‖ \left‖ \left‖ \left‖ x^2 
    \right‖^2 \right‖^2 \right‖^2 \right‖^2 \right‖^2 \right‖ \]

\[ \left\Vert \left\Vert \left\Vert \left\Vert \left\Vert \left\Vert x^2 
    \right\Vert^2 \right\Vert^2 \right\Vert^2 \right\Vert^2 \right\Vert^2 \right\Vert \]
\end{document}