In the figure form, how to adjust the whole size of "text" and "math" format at once?

Question

In the figure form, how to adjust the whole size of "text" and "math" format "as a combined figure" at once?

If this is a usual pdf figure, we can do \includegraphics[width=4.4in], such as below, the size is tuned by [width=4.4in]

\begin{figure}[htbp]
  \centering
  \includegraphics[width=4.4in]{.pdf}
  \caption{}\label{}
\end{figure}

Can we adjust the whole overall size of the figure (including the "text" and "math" format) at once by the similar function, like "size"?

I hope to have a 3-times-larger figure overall.

\documentclass{article}
\usepackage{mathtools,amssymb}
\begin{document}

\begin{figure}[!h]
\begin{center}
\begin{gather*}
\overbrace{\underbrace{A \times B}_E\times
           \underbrace{C\times {D}}_{EFG}}^{\text{ABCDEFG}} \\[-\normalbaselineskip]
\underbrace{\kern5em}_{\text{family}}
\end{gather*}
\end{center}
\caption{}
\end{figure}
\end{document}

Answer 1

\documentclass[fleqn]{article}
\usepackage{mathtools,amssymb,varwidth}
\usepackage{showframe}
\begin{document}

\begin{figure}[!htb]
\resizebox{\linewidth}{!}{%
  \begin{varwidth}{\linewidth}
  \mathindent=0pt
  \begin{gather*}
    \overbrace{\underbrace{A \times B}_E\times
               \underbrace{C\times {D}}_{EFG}}^{\text{ABCDEFG}}\\[-\normalbaselineskip]
    \underbrace{\hphantom{A\times B\times C\times D}}_{\text{family}}
    \end{gather*}
  \end{varwidth}}
  \caption{foo}
\end{figure}
\end{document}

Instead of \resizebox you can also use \scalebox:

[...]
\begin{figure}[!htb]
\centering
\scalebox{3}{%
  \begin{varwidth}{\linewidth}
[...]

Answer 2

If you want to resize content using a specific width/height, then you can use \resizebox{<width>}{<height>} (using ! to maintain the aspect ratio if you only specify one or the other). If you want to scale content using a number, you can use \scalebox{<num>}:

\documentclass{article}

\usepackage{graphicx,amsmath}

\begin{document}

\begin{figure}
  \centering
  \scalebox{3}{$\displaystyle % If needed...
    \underbrace{
      \overbrace{
        \underbrace{
          A \times B
        }_E \times \underbrace{
          C \times D
        }_{EFG}
      }^{\text{ABCDEFG}}
    }_{\text{family}}
  $}
  \caption{A caption}
\end{figure}

\end{document}

I've nested the family \underbrace as part of the bigger expression, so there's no need to manually place it based on the location. Also note the use of \centering rather than the center environment, and there's no need for using gather.