% !TEX program = luahbtex

\input luaotfload.sty
\parindent=0pt
\parskip=0pt

\def\fonttest#1{%
  \font\testfont="#1"\relax
  {\testfont ABCDEFGHIJKLM}\par}

\fonttest{Skia}
\fonttest{Skia:instance=Light Extended}
\fonttest{Skia:mode=harf;instance=Light Extended}

\bigskip

\fonttest{[STIXTwoText-Italic.ttf]}
\fonttest{[STIXTwoText-Italic.ttf]:instance=SemiBold Italic}
\fonttest{[STIXTwoText-Italic.ttf]:mode=harf;instance=SemiBold Italic}

\bye