\input luaotfload.sty

\font\testa={LM Roman Slanted 10 Regular} at 10pt
\font\testb={LM Roman 9 Italic}           at 10pt
\font\testc={TeX Gyre Termes Bold}        at 25pt
\testa abcd ABCD\par
\testb abcd ABCD\par
\testc abcd ABCD\par
\bye