\documentclass[]{cv}

\usepackage[ngerman]{babel}

\MakeHeader{Anton Lydike}{17. Sep. 2022}

\begin{document}
    
\section[testsec]{Test öäüßẞ ẞ Section}

    Hello world öäüß ẞ

    \subsection{Subsection öäüß test}

\end{document}