First, side remark, if I compile the linked example I do not get the same typeface as in your screenshot for the chapter titles. Second, yes loading etoc apparently undoes the modification done by classicthesis to the global TOC style. But there is \etockeeporiginaltableofcontents
which allows \tableofcontents
to retain a non-etoc behaviour.
Code from https://tex.stackexchange.com/a/588678/306222 solely modified via addition of \etockeeporiginaltableofcontents
.
\documentclass[a4paper]{report}
\usepackage{kantlipsum} % dummy text <<<<
\usepackage{classicthesis}
\usepackage{etoc} % added <<<<<<<<<<<<
\etockeeporiginaltableofcontents
\begin{document}
\tableofcontents
\etocsettocstyle{\vskip0.3\baselineskip}{\noindent\rule{\linewidth}{0.5pt}\vskip0.5\baselineskip} % etoc style for local TOC
\chapter{Apple}
\localtableofcontents %<<<<<<<<<<<<<<
1. \kant[1]
\section{Alabama}
2. \kant[2-4]
\section{Arizona}
3. \kant[5-7]
\subsection{Afghanistan}
4. \kant[8-9]
\subsection{Austria}
4. \kant[10-12]
\chapter{Banana}
\localtableofcontents %<<<<<<<<<<<<<<
6. \kant[14]
\section{Split}
7. \kant[15]
\chapter{Cherry}
\localtableofcontents %<<<<<<<<<<<<<<
7. \kant[18]
\end{document}