\usepackage[greek.ancient,english]{babel}
\babeltags{grc = greek}
\babelfont{rm}{Old Standard}
\babelfont[greek]{rm}[RawFeature={+ss05;+ss06}]{Old Standard}
\usepackage[greek.ancient,english]{babel}
\babeltags{grc = greek}
\babelfont{rm}{Old Standard}
\babelfont[greek]{rm}[RawFeature={+ss05;+ss06}]{Old Standard}