\documentclass{article}

\usepackage{geometry}
\usepackage{ulem}
\usepackage{listings}
\usepackage{hyperref}
\usepackage{xcolor}
\usepackage{indentfirst}
\usepackage{enumitem}

    \hypersetup{
        colorlinks=true,
        linkcolor=blue,
        filecolor=magenta,
        urlcolor=blue,
    }
\begin{document}
 
\setcounter{secnumdepth}{0}

\section{Heading 1}

\begin{itemize}
    \item item 1
    \begin{itemize}
        \item nested item 1
        \begin{itemize}
            \item nested nested
        \end{itemize}

        \item nested item 2
    \end{itemize}

    \item item 2
    \item item 3
\end{itemize}

\subsection{Heading 2}

\begin{itemize}
    \item item 1
    \begin{itemize}
        \item nested item 1
        \begin{itemize}
            \item nested nested
        \end{itemize}

        \item nested item 2
    \end{itemize}

    \item item 2
    \item item 3
\end{itemize}

\end{document}