How to prevent PNG and JPG files from oversizing for no reason?

Question

I am using Revtext 4.2 documents with 2 columns. I tried to add a picture by using the following line of code:

\begin{figure}[b]
    \includegraphics[width=\textwidth]{grad}
    \caption{Visualization of Gradient Descent}
    \label{fig:Gradient}
\end{figure}    

This blew up the size of the picture and was about half a page big. Here is a picture of what it looked like:

I have try to use the solution presented in this thread enter link description here

And rewrote my code as such:

\begin{figure}
    \includegraphics[width=\textwidth,height=\textheight,keepaspectratio]{grad}
    \caption{Visualization of Gradient Descent}
    \label{fig:Gradient}
\end{figure}    

which only made it worse:

Full code with similar effect:

\documentclass[%
 reprint,
%superscriptaddress,
%groupedaddress,
%unsortedaddress,
%runinaddress,
%frontmatterverbose, 
%preprint,
%preprintnumbers,
%nofootinbib,
%nobibnotes,
%bibnotes,
 amsmath,amssymb,
 aps,
%pra,
%prb,
%rmp,
%prstab,
%prstper,
%floatfix,
]{revtex4-2}
\usepackage{graphicx}% Include figure files
\usepackage{dcolumn}% Align table columns on decimal point
\usepackage{bm}% bold math
%\usepackage{hyperref}% add hypertext capabilities
%\usepackage[mathlines]{lineno}% Enable numbering of text and display math
%\linenumbers\relax % Commence numbering lines
%\usepackage[showframe,%Uncomment any one of the following lines to test 
%%scale=0.7, marginratio={1:1, 2:3}, ignoreall,% default settings
%%text={7in,10in},centering,
%%margin=1.5in,
%%total={6.5in,8.75in}, top=1.2in, left=0.9in, includefoot,
%%height=10in,a5paper,hmargin={3cm,0.8in},
%]{geometry}
\usepackage{physics}
\usepackage{tikz}
\usepackage{caption}
\usetikzlibrary{quantikz}
\DeclareUnicodeCharacter{2212}{-}
\begin{document}
\date{\today}
\maketitle
\begin{figure}
    \includegraphics[width=\textwidth,height=\textheight,keepaspectratio]{grad}
    \caption{Visualization of Gradient Descent}
    \label{fig:Gradient}
\end{figure}
\bibliographystyle{plain}
\nocite{*}
\bibliography{reference.bib}
\end{document}