\documentclass{article}
\usepackage{amsmath}
\usepackage{hyperref}
\usepackage{fontspec}
\usepackage{unicode-math}
\usepackage{hologo}
\usepackage{graphicx}
\begin{document}
\setmathfont{STIX2Math}[
Extension={.otf},
Path=./STIX2fonts/,
Scale=1]
\setmainfont{STIX2Text}[
Extension={.otf},
Path=./STIX2fonts/,
UprightFont={*-Regular},
BoldFont={*-Bold},
ItalicFont={*-Italic},
BoldItalicFont={*-BoldItalic}]
\title{Using the STIX2 OpenType fonts with \hologo{LuaLaTeX} or \hologo{XeLaTeX}}
\author{Graham Douglas}
\maketitle
\section*{About this template}
This template provides convenient access to the STIX2 OpenType fonts, which are loaded into the folder \texttt{STIX2fonts}. Using the \texttt{fontspec} and \texttt{unicode-math} packages, the fonts are configured ready for use with \hologo{XeLaTeX} or \hologo{LuaLaTeX}---you can choose either engine via Overleaf's Menu: \lower5pt\hbox{\includegraphics{olmenu.png}}.
\section*{Some examples}
The following \LaTeX{} examples are taken from:\vskip10pt \noindent \url{https://en.wikibooks.org/wiki/LaTeX/Advanced_Mathematics}
\begin{align*}
&\vdots\\
&=12+7 \int_0^2
\left(
-\frac{1}{4}\left(e^{-4t_1}+e^{4t_1-8}\right)
\right)\,dt_1\displaybreak[3]\\
&= 12-\frac{7}{4}\int_0^2 \left( e^{-4t_1}+e^{4t_1-8} \right)\,dt_1\\
&\vdots %
\end{align*}
\begin{equation}
x = a_0 + \frac{1}{\displaystyle a_1
+ \frac{1}{\displaystyle a_2
+ \frac{1}{\displaystyle a_3 + a_4}}}
\end{equation}
\begin{alignat}{2}
\sigma_1 &= x + y &\quad \sigma_2 &= \frac{x}{y} \\
\sigma_1' &= \frac{\partial x + y}{\partial x} & \sigma_2'
&= \frac{\partial \frac{x}{y}}{\partial x}
\end{alignat}
\fbox{
\addtolength{\linewidth}{-2\fboxsep}%
\addtolength{\linewidth}{-2\fboxrule}%
\begin{minipage}{\linewidth}
\begin{equation}
x^2+y^2=z^2
\end{equation}
\end{minipage}
}
\[
\lim_{x\to 0}{\frac{e^x-1}{2x}}
\overset{\left[\frac{0}{0}\right]}{\underset{\mathrm{H}}{=}}
\lim_{x\to 0}{\frac{e^x}{2}}={\frac{1}{2}}
\]
\end{document}
