%%
%% The LaTeX Companion, 3ed
%%
%% Example 9-6-22 on page I-724 in "Stylistic features".
%%
%% Copyright (C) 2022 Frank Mittelbach
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3c
%% of this license or (at your option) any later version.
%%
%% See https://www.latex-project.org/lppl.txt for details.
%%

\documentclass{tlc3exa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{87.0pt}

  %!TEX program = lualatex

  \setlength\parindent{0pt}

%StartShownPreambleCommands
\usepackage{fontspec} \setmainfont{Libertinus Serif}
%StopShownPreambleCommands

\begin{document}
Ä Ü Ö     \quad   {\addfontfeature{StylisticSet=1}Ä Ü Ö}          \\
J K R     \quad   {\addfontfeature{StylisticSet=2}J K R}          \\
Gruß \textsc{Gruß} GRU\SS                                         \\
    {\addfontfeature{StylisticSet=3}Gruß \textsc{Gruß} GRU\SS}    \\
    {\addfontfeature{StylisticSet=4}Gruß \textsc{Gruß} GRU\SS}    \\
 W        \quad   {\addfontfeature{StylisticSet=5}W}          \qquad
\&        \quad   {\addfontfeature{StylisticSet=6}\&}             \\
JKQRW hy ß \& \\  {\addfontfeature{Style=Alternate}JKQRW hy ß \&} \\
         {\addfontfeature{StylisticSet={1,2,4,5,6}}JKQRW hy ß \&}
\end{document}