\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{tcolorbox}
\usepackage{lipsum}
\usepackage{titlesec}
\titleformat{\section}
{}
{}
{0em}
{\paulocoloredsection}
\newcommand{\paulocoloredsection}[1]{%
\begin{tcolorbox}[
height=0.7cm,
valign=center,
colback=green!50!black,
arc=0pt,
outer arc=0pt,
boxrule=0mm,
nobeforeafter,
]\Large\bfseries\textcolor{white}{#1}
\end{tcolorbox}%
}
\begin{document}
\section{Hello}