\documentclass[10pt]{article}
\usepackage[UTF8]{ctex}
\usepackage{geometry}
\usepackage{graphicx}
\usepackage{amsmath}
\usepackage{array}
\usepackage{booktabs}
\usepackage{longtable}
\usepackage{setspace}
\usepackage{fancyhdr}
\usepackage{titlesec}
\usepackage{tabularx}
\usepackage{makecell}
\usepackage{adjustbox}
\usepackage{hyperref}
% 页面设置
\geometry{margin=2cm}
\setlength{\parskip}{1em}
\setlength{\parindent}{0em}

% 字体
\setCJKmainfont{Noto Serif CJK SC}

% 标题样式
\title{\Large \textbf{$title$}}
\author{}
\date{}

% 章节标题样式
\titleformat{\section}{\large\bfseries\raggedright}{\thesection}{1em}{}
\titleformat{\subsection}{\normalsize\bfseries\raggedright}{\thesubsection}{1em}{}


% ===== Pandoc compatibility =====
\usepackage{hyperref}
\providecommand{\tightlist}{%
  \setlength{\itemsep}{0pt}\setlength{\parskip}{0pt}}


\begin{document}

\maketitle

$body$

\end{document}