documentclass{article}
usepackage{enumitem,kantlipsum}
begin{document}
  begin{enumerate}[label=arabic*., listparindent=1.5em]
    item kant[1-2]
    item kant[3-4]
  end{enumerate}
end{document}

documentclass{article}
usepackage{enumitem,kantlipsum}
begin{document}
  begin{enumerate}[label=arabic*., listparindent=1.5em, labelsep=2em, itemindent=1.5em]
    item kant[1-2]
    item kant[3-4]
  end{enumerate}
end{document}