\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}