An example of how you can use TikZ and absolute positioning to create fancy chapter headings.

Edit and compile if you like:
% Fancy chapter headings
% Author: Stefan Kottwitz
% Source: http://texblog.net/latex-archive/layout/fancy-chapter-tikz/
\documentclass[svgnames]{report}
\usepackage{tikz}
\usepackage{kpfonts}
\usepackage[explicit]{titlesec}
\newcommand*\chapterlabel{}
\titleformat{\chapter}
{\gdef\chapterlabel{}
\normalfont\sffamily\Huge\bfseries\scshape}
{\gdef\chapterlabel{\thechapter\ }}{0pt}
{\begin{tikzpicture}[remember picture,overlay]
\node[yshift=-3cm] at (current page.north west)
{\begin{tikzpicture}[remember picture, overlay]
\draw[fill=LightSkyBlue] (0,0) rectangle
(\paperwidth,3cm);
\node[anchor=east,xshift=.9\paperwidth,rectangle,
rounded corners=20pt,inner sep=11pt,
fill=MidnightBlue]
{\color{white}\chapterlabel#1};
\end{tikzpicture}
};
\end{tikzpicture}
}
\titlespacing*{\chapter}{0pt}{50pt}{-60pt}
\begin{document}
\tableofcontents
\chapter{Introduction}
Text
\chapter{Main}
\section{Section}
Text
\begin{thebibliography}{99}
\bibitem{Test} test reference
\end{thebibliography}
\end{document}Click to download: fancy-chapter-headings.tex • fancy-chapter-headings.pdf
Open in Overleaf: fancy-chapter-headings.tex