Is it possible to use \addfontfeature for specific characters? Something like this MWE in order to get every e of the document with double size:
\usepackage{fontspec}
\usepackage{hyperref}
\setmainfont{Latin Modern}
\setmainfont{Latin Modern}[Scale=2.0, range = {e}]
\begin{document}
Test
\end{document}