\documentclass{article}

\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{87.0pt}

% Special setting to make delimiters always grow in this example
\setlength\delimitershortfall{-3pt}

\usepackage{bm}
\begin{document}

\begin{equation}
  a^2+\mathbf{b^2}=c^2
\end{equation}
$\bm{\Biggl\lbrace\biggl\lbrace\Bigl\lbrace\bigl\lbrace \lbrace
     \mathcal{Q}
     \rangle \bigr\rangle\Bigr\rangle\biggr\rangle\Biggr\rangle}$
\mathversion{bold}
\begin{equation}
  a^2+b^2=c^2
\end{equation}

\end{document}