\documentclass{article}
\usepackage[margin=0.25in]{geometry}
\usepackage{pgfplots}
\pgfplotsset{width=10cm,compat=1.9}

%borrowed from overleaf's tutorial https://www.overleaf.com/learn/latex/Pgfplots_package on 3/19/24

\begin{document}

First example is 2D and 3D math expressions plotted side-by-side.

%Here begins the 2D plot
\begin{tikzpicture}
\begin{axis}
\addplot[color=red]{exp(x)};
\end{axis}
\end{tikzpicture}
%Here ends the 2D plot
\hskip 5pt
%Here begins the 3D plot
\begin{tikzpicture}
\begin{axis}
\addplot3[
    surf,
]
{exp(-x^2-y^2)*x};
\end{axis}
\end{tikzpicture}
%Here ends the 3D plot

\end{document}