How to make custom section title placement and size

Probably something like this

documentclass{article}
usepackage[compact]{titlesec}% http://ctan.org/pkg/titlesec
titleformat{section}
{normalfontLargebfseries}{thesection}{0pt}{hfill}[{titlerule[0.8pt]}]
titlespacing*{section}
{0em} %left
{0em} %before
{1em} %after/below
begin{document}

    section{Introduction}
    This is some regular text.
end{document}

edit to conform better to OP requirement

adapted from --

How to get custom section style using titlesec?

documentclass{article}
usepackage[explicit]{titlesec}
usepackage{lmodern}
usepackage{lipsum}
usepackage{multirow}

usepackage[table]{xcolor}

usepackage{tabularx}
usepackage{ctable}
newcolumntype{C}{>{raggedleftarraybackslash}X}

titleformat{section}[block]{Largebfseriessffamily}%
{}%
{0pt}%
{%
    begin{tabularx}{textwidth}{lC}
       multirow{-2.5}{*}{fontsize{70}{30}selectfontnormalfontthesection} & #1\arrayrulecolor{red!50!black}cmidrule[4pt]{2-2}
    end{tabularx}
    %
}
begin{document}
    section {Introduction}
    lipsum[4]
end{document}