I want to change the display style of chapters in my document. I use the fncychap package. Here are the settings :
\usepackage[glenn]{fncychap} % Pour changer les chapitres
\ChNameVar{\bfseries\Large\sf}
\ChNumVar{\Huge}
\ChTitleVar{\bfseries\Large\rm}
\ChRuleWidth{1pt}
\ChNameUpperCase
\ChTitleUpperCase
When I run my code, the style doesn't change. I didn't find anything here or on internet about this issue. Here is my preamble :
\documentclass[10pt,a4paper,twocolumn,twoside]{book}
% Format + encodage
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[french]{babel}
% ----------------------------------------
% Package pour la conception d'un document
% ----------------------------------------
\usepackage{ifdraft}
\usepackage{lipsum}
%\usepackage{layouts}
\usepackage[obeyFinal]{easy-todo}
%\usepackage[obeyDraft]{todonotes} % Pour des boites dans la marge
% ----------------------------
% Packages pour la mise en page
% ----------------------------
\usepackage{booktabs}
\usepackage{cellspace}
\usepackage{makecell}
%\setcellgapes{3pt}
\usepackage{stackengine,scalerel}
\usepackage{lscape}
\usepackage{calc}
\usepackage[full]{textcomp}
\usepackage[inner=3cm,outer=1cm,top=3cm,bottom=3cm]{geometry} % Mise en page type livre
\usepackage{setspace} % \singlespacing ; \onehalfspacing ; \doublespacing
\usepackage{hyperref}
\usepackage{float}
\usepackage{pdfpages}
\usepackage{changepage} % Pour adjustwidth
\usepackage[babel=true,kerning=true]{microtype}
% modification des titres
%\usepackage{titlesec} % Pour changer l'apparence des titres
% =======================================================
\usepackage[glenn]{fncychap} % Pour changer les chapitres
\ChNameVar{\bfseries\Large\sf}
\ChNumVar{\Huge}
\ChTitleVar{\bfseries\Large\rm}
\ChRuleWidth{1pt}
\ChNameUpperCase
\ChTitleUpperCase
% -------------------------------------------------------
\usepackage{fontawesome} % Pour rajouter des symboles
\usepackage{lettrine} % Pour avoir des lettrines
\usepackage{wrapfig}
\usepackage{sectsty} % Pour changer la couleur des titres
% ----------------------------
% Packages pour le mode math
% ----------------------------
\usepackage{amsthm}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{mathrsfs}
\usepackage{mathtools}
\usepackage{esint}
\usepackage[g]{esvect}
% ----------------------------
% Packages pour le dessin
% ----------------------------
\usepackage{xcolor}
\usepackage{tikz}
\usepackage{pgfplots}
\usepackage{colortbl}
\usepackage[tikz]{bclogo}
\usepackage{graphicx}
\usepackage{mdframed}
\usepackage{stmaryrd}
\usepackage{fancybox}
% libraries Tikz
\usetikzlibrary{decorations.pathmorphing}
\usetikzlibrary{decorations.pathreplacing}
\usetikzlibrary{decorations.shapes}
\usetikzlibrary{decorations.text}
\usetikzlibrary{angles}
\usetikzlibrary{decorations.markings}
\usetikzlibrary{decorations.fractals}
\usetikzlibrary{decorations.footprints}
\usetikzlibrary{patterns}
\usetikzlibrary{plotmarks}
% ---------------------------------
% En-tête et pied de page
\usepackage{fancyhdr}
\pagestyle{fancy}
\usepackage{lastpage}
\renewcommand\headrulewidth{1pt}
\fancyhead[L]{\emph{Les petits carnets de l'ingénieur}}
\fancyhead[R]{Nicolas \textsc{Lesquoy}}
%\renewcommand\footrulewidth{1pt}
\fancyfoot[C]{\textbf{Page \thepage}}
\fancyfoot[R]{\today}
\fancyfoot[L]{\textsc{ISAE-Supaero}}
% ----------------------------
% Packages pour le choix de la police
% ----------------------------
\usepackage{kpfonts}
\usepackage{addfont} % Pour les lettres cursives très jolies
\addfont{OT1}{rsfs10}{\rsfs}
\usepackage{pgothic}
\usepackage{calligra}
% ----------------------------
% Packages pour présenter du code
% ----------------------------
\usepackage{listings}
\lstdefinestyle{pprint}{
language=Python,
breaklines=true,
basicstyle=\footnotesize\ttfamily,
keywordstyle=\bfseries\color{green!40!black},
commentstyle=\itshape\color{gray!40},
stringstyle=\color{violet},
numberstyle=\tiny,
keepspaces=true,
numbers=left,
%frame=single,
%framesep=2pt,
aboveskip=1ex,
showtabs=true,
captionpos=b
} % Python
\lstset{literate=
{á}{{'a}}1 {é}{{'e}}1 {í}{{'i}}1 {ó}{{'o}}1 {ú}{{'u}}1
{Á}{{'A}}1 {É}{{'E}}1 {Í}{{'I}}1 {Ó}{{'O}}1 {Ú}{{'U}}1
{à}{{`a}}1 {è}{{`e}}1 {ì}{{`i}}1 {ò}{{`o}}1 {ù}{{`u}}1
{À}{{`A}}1 {È}{{'E}}1 {Ì}{{`I}}1 {Ò}{{`O}}1 {Ù}{{`U}}1
{ä}{{"a}}1 {ë}{{"e}}1 {ï}{{"i}}1 {ö}{{"o}}1 {ü}{{"u}}1
{Ä}{{"A}}1 {Ë}{{"E}}1 {Ï}{{"I}}1 {Ö}{{"O}}1 {Ü}{{"U}}1
{â}{{^a}}1 {ê}{{^e}}1 {î}{{^i}}1 {ô}{{^o}}1 {û}{{^u}}1
{Â}{{^A}}1 {Ê}{{^E}}1 {Î}{{^I}}1 {Ô}{{^O}}1 {Û}{{^U}}1
{œ}{{\oe}}1 {Œ}{{\OE}}1 {æ}{{\ae}}1 {Æ}{{\AE}}1 {ß}{{\ss}}1
{ű}{{\H{u}}}1 {Ű}{{\H{U}}}1 {ő}{{\H{o}}}1 {Ő}{{\H{O}}}1
{ç}{{\c c}}1 {Ç}{{\c C}}1 {ø}{{\o}}1 {å}{{\r a}}1 {Å}{{\r A}}1
{€}{{\euro}}1 {£}{{\pounds}}1 {«}{{\guillemotleft}}1
{»}{{\guillemotright}}1 {ñ}{{~n}}1 {Ñ}{{~N}}1 {¿}{{?`}}1
{°}{{\degres}}1
} % Problème d'encodage
The document is composed of differents .tex files which are included in my main.tex file with \input{file}.
Could someone help me solving this issue ?

sectstybeforefncychap. But think twice before using the latter package, which produce very dubious results from a typographical point of view. – egreg Aug 18 '21 at 20:57Glenn, notglenn. And it produces one of the worst chapter heading I have ever seen. – egreg Aug 19 '21 at 10:19