\documentclass[12pt]{article}
%Xwrizw kwd. keimenou 
\usepackage[utf8]{inputenc}
%Xwrizw kwd. seiras
\usepackage[T1]{fontenc}
\usepackage[english]{babel}
\author{Ntotis Apostolos}
\title{My first title}
\date{2/3/23}
\begin{document}
\maketitle
\newpage
\tableofcontents
\newpage
\section{My first section}
This is my first section! Δοκιμή πρώτη!
\subsection{My first subsection}
This is my first subsection!!
\end{document}
