\DocumentMetadata{
  pdfversion=2.0,
  pdfstandard=ua-2,
  lang=en-US,
}
\documentclass[12pt]{letter}

\usepackage{fontspec}
% fontspec disables the classic TeX input ligatures by default
% (-- => en-dash, --- => em-dash, `` and '' => curly quotes), so
% re-enable them globally for every font loaded below.
\defaultfontfeatures{Ligatures=TeX}
\setmainfont{Libertinus Serif}
% Mako prefers Adobe Garamond Premier Pro
% (https://fonts.adobe.com/fonts/garamond-premier-pro). It is a
% commercial font and is not redistributable, so the templates default
% to the free Libertinus Serif above. If you have the font installed
% (e.g., dropped into ~/.fonts/), comment the line above and uncomment
% the next one. CDSC members can contact Mako (mako@atdot.cc) for the
% font files.
% \setmainfont{Garamond Premier Pro}
\setsansfont{TeX Gyre Heros}

\usepackage[letterpaper,left=1.3in,right=1.3in,top=0.8in,bottom=0.8in]{geometry}

\usepackage{tagpdf}
\tagpdfsetup{activate-all}

\usepackage{hyperref}
\hypersetup{unicode=true,
    pdftitle={Letter},
    pdfauthor={Benjamin Mako Hill},
    pdflang={en-US},
    pdfdisplaydoctitle=true}

\begin{document}

\begin{letter}{Person Letter is Addressed To\\
Followed by Address}

\address{Benjamin Mako Hill\\
Massachusetts Institute of Technology\\
Room E15-312\\
20 Ames Street\\
Cambridge, MA 02139-4307}

\signature{Benjamin Mako Hill}

\location{Massachusetts Institute of Technology\\
Room E15-020c\\
20 Ames Street\\
Cambridge, MA 02139-4307}

\telephone{(206) 409-7191} 

\opening{To whom it may concern,}
\setlength\parindent{0.25in}

Text of Letter goes here. Text of Letter goes here. Text of Letter
goes here. Text of Letter goes here. Text of Letter goes here. Text of
Letter goes here. Text of Letter goes here. Text of Letter goes
here. Text of Letter goes here.

\closing{Regards,}

\end{letter}

\end{document}