\documentclass[12pt]{amsart}
% \usepackage[margin=1in]{geometry} % Normal (small) font
% \usepackage[margin=0.4in,paperwidth=480pt,paperheight=690pt]{geometry} % Medium font (~6.7in x ~9.6in): roughly 1.2^2 = 1.44 times normal size
\usepackage[margin=0.4in,paperwidth=400pt,paperheight=575pt]{geometry} % Large font (~5.6in x ~8.0in): roughly 1.44^2 ~ 2.07 times normal size

\begin{document}

\title{Larger amsart fonts for drafting}
\author{Victor Wang}
\date{\today}

\begin{abstract}
Larger fonts may be good for reducing eyestrain while drafting,
but 12pt seems to be the default limit in amsart, which this template allows one to easily surpass and customize.
\end{abstract}

\maketitle

\tableofcontents

\section{Introduction}

Hello world

\section{Conclusion}

Hello world

\end{document}