\documentclass{book}
\usepackage{glossaries-extra}
\newabbreviation{xxx}{asa}{a simple abbreviation}

\begin{document}
%\chapter{A chapter}
\section{A section}
\gls{xxx}

\glsfmtname{xxx} 

\Glsfmtname{xxx} 

\GLSfmtname{xxx} 




\end{document}






