\documentclass[a5paper]{article}
%\usepackage[utf8]{inputenc}
\usepackage[LGR,T1]{fontenc}
\usepackage{lmodern}
\usepackage[greek.polutoniko,french]{babel}
\languageattribute{greek}{ancient}
\begin{document}
un  texte en alphabet latin\par
\textgreek{Σώστρατε, ἐρῶν άπῆλθες εὐθύς}
un autre
\end{document}
