\documentclass[12pt]{article}

\usepackage[number in = section]{fancythm}

\makeatletter
%\@counteralias{insection}{indocument}
\makeatother

\ExplSyntaxOff

\AddProvidedFancyTheoremToGroup{lemma}{small}

\begin{document}

\section{test}

\stepcounter{toplevel}


\begin{example}
  test
\end{example}

\begin{example}+
  test
\end{example}

\begin{example}*
  
\end{example}

\begin{lemma}
  
\end{lemma}

\begin{definition}
  test
\end{definition}

\begin{definition}*
  bla
\end{definition}

\begin{theoremdef}
  test
\end{theoremdef}



\begin{goal}+
  test
\end{goal}


\end{document}