\documentclass{testsuite}
\usepackage{fontspec}
\renewcommand\eminnershape{\upshape\scshape}
\begin{document}
\setmainfont[
    ItalicFont=texgyrepagella-italic.otf
  ]{texgyrepagella-regular.otf}
hello \emph{emph \emph{2emph} emph} hello

hello {\em emph {\em 2emph} emph} hello
\end{document}