\documentclass[14pt]{extarticle}
\usepackage[paperheight=8.5in,
   paperwidth=11in,
   top=10mm,
   bottom=10mm,
   left=10mm,
   right=10mm]{geometry}
\usepackage{graphicx} % Required for inserting images
\usepackage{xcolor} % Required to define colour
\usepackage{librebaskerville}
\usepackage{nunito}
\usepackage{pgf}
\usepackage{pgfpages}

\definecolor{gold}{RGB}{186, 159, 104} % fonts and colours
\definecolor{canadianred}{RGB}{254, 0, 0}
\definecolor{coolgrey}{RGB}{42, 52, 66}

\def\changemargin#1#2{\list{}{\rightmargin#2\leftmargin#1}\item[]}
\let\endchangemargin=\endlist

\title{MEMBER SHARE CERTIFICATE}
\author{Dawn Walker}
\date{\today}

\makeatletter
\let\printtitle\@title
\let\printauthor\@author
\let\printdate\@date
\makeatother

\pgfpagesdeclarelayout{boxed}
{
  \edef\pgfpageoptionborder{0pt}
}
{
  \pgfpagesphysicalpageoptions
  {%
    logical pages=1,%
  }
  \pgfpageslogicalpageoptions{1}
  {
    border code=\pgfsetlinewidth{3pt}\pgfsetstrokecolor{coolgrey}\pgfstroke,%
    border shrink=\pgfpageoptionborder,%
    resized width=.98\pgfphysicalwidth,%
    resized height=.95\pgfphysicalheight,%
    center=\pgfpoint{.498\pgfphysicalwidth}{.5\pgfphysicalheight}%
  }%
}

\pgfpagesuselayout{boxed}
\begin{document}
\pagenumbering{gobble}

\begin{figure}
    \centering
    \vspace{1cm}
    \includegraphics[width=6.5cm]{Lockup_Colour.png}
    \vspace{0.4cm}
\end{figure}

\centering\textcolor{gold}{\huge\librebaskerville \textbf{\printtitle}}

\vspace{0.6cm}

\begin{changemargin}{2cm}{2cm}

\begin{flushright}
    Certificate \# \underline{ $certificate$ }
\end{flushright}

\vspace{1.6cm}

\noindent This certifies that \underline{ $member_name$ } is the record holder of \underline{ one ( 1 ) } member share(s) of \textbf{\mbox{CoSocial} Community Cooperative} with a \textbf{par value of ten Canadian dollars ( \textdollar10 )}. \newline

\noindent Your membership was approved and entered in the Cooperative’s register on \underline{ $join_date$ }.

\vspace{1cm}

\begin{figure}[h!]
    \hspace*{1.7cm}
    \includegraphics[width=3cm]{President_Signature.png}
\end{figure}
\noindent \printauthor \\
President, Board of Directors \\
CoSocial Community Cooperative

\end{changemargin}

\end{document}