Move chapter to top and change its format

Question

I would like to change position of my chapter title more to the top of the page and also change format of it to: "0 Introduction" "1 Something" "1.1 Something" "2 Something" etc. instead of "Chapter 1 - Something"

and also, how do I change the distance between chapter title and beginning of the text?

Thank you very much for any advice.

Answer 1

Use the memoir class (a superset of book and report) with the section chapter style.

% chapstyleprob.tex  SE 567585
\documentclass{memoir}
\usepackage{lipsum}

\chapterstyle{section} %% this seems to be the style you want
\setlength{\beforechapskip}{-1cm} %% raise title, adjust to suit
\begin{document}
\setcounter{chapter}{-1}  %% first chapter number will be 0
\chapter{Introduction}
\thispagestyle{empty}
\lipsum[1]
\section{First section}
\lipsum[2]
\end{document}