%%
%% The LaTeX Companion, 3ed
%%
%% Example 12-4-6 on page II-260 in "Adjusting parts of the font setup".
%%
%% 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{99.0pt}

  % typeset with lualatex

  \setlength\parindent{0pt}

%StartShownPreambleCommands
\usepackage{fontspec}     \setmainfont{Fira Sans}     % text setup
\usepackage{unicode-math} \setmathfont{Fira Math}     % math setup
\setmathfont{STIX Two Math Regular}[range={frak,scr}] % replacement
%StopShownPreambleCommands

\begin{document}
Scripts: $A \neq \symscr{A} \neq \symbb{A} \neq \symfrak{A}$
\end{document}