LaTeX Forum

\documentclass[12pt]{scrartcl}
\usepackage{authblk}
\usepackage[english,main=ngerman]{babel}
\usepackage[babel]{csquotes}
\usepackage[T1]{fontenc}
\usepackage{newtxtext}
\usepackage{graphicx}				
\usepackage{geometry}
\usepackage{microtype}                		
%\geometry{a4paper} 					
\usepackage{setspace}

\usepackage[maxcitenames=5, citestyle=authoryear-ibid, style=authoryear, autocite=footnote, maxbibnames=99]{biblatex}
\DefineBibliographyStrings{german}{ 
  andothers = {et al} 
} 

\DefineBibliographyStrings{ngerman}{ 
   andothers = {{et\,al\adddot}}, 
}

\renewcommand{\thesection}{\Alph{section}}
\renewcommand{\thesubsection}{\Roman{subsection}}
\renewcommand{\thesubsubsection}{\arabic{subsubsection}}

\setcounter{secnumdepth}{\subparagraphnumdepth}
\setcounter{tocdepth}{\subparagraphtocdepth}


\setcounter{secnumdepth}{\subsubparagraphnumdepth}
\setcounter{tocdepth}{\subsubparagraphtocdepth}


\RedeclareSectionCommand[%
  beforeskip=-0.5\baselineskip,
  afterskip=0.5\baselineskip,
  tocindent=7em, 
  tocnumwidth=2.1em
]{paragraph}

\RedeclareSectionCommand[%
  beforeskip=-0.25\baselineskip,
  afterskip=0.25\baselineskip
]{subparagraph}

\DeclareSectionCommand[,
    indent=0pt,
      tocindent=9.2em, 
     tocnumwidth=3em
  ]{subparagraph}
 
\RedeclareSectionCommand[%
  beforeskip=-0.25\baselineskip,
  afterskip=0.25\baselineskip
]{subsubparagraph}

\DeclareSectionCommand[,
    indent=0pt,
      tocindent=9.2em, 
     tocnumwidth=3em
  ]{subsubparagraph}

\usepackage[automark,headsepline,markcase=noupper]{scrlayer-scrpage} 
\clearmainofpairofpagestyles 
\ihead{\leftmark} 
\ohead{\pagemark} 
\setkomafont{pageheadfoot}{\normalfont\normalcolor}            		 
\usepackage{hyperref}
\urlstyle{same}

\begin{document}

\tableofcontents

\section{A}

\subsection{B}

\paragraph{C}

\subparagraph{D}

\subsubparagraph{E}

\end{document}

\documentclass[12pt]{scrartcl}
\usepackage{authblk}
\usepackage[english,main=ngerman]{babel}
\usepackage[babel]{csquotes}
\usepackage[T1]{fontenc}
\usepackage{newtxtext}
\usepackage{graphicx}
%\usepackage{geometry}
\usepackage{microtype}
%\usepackage{setspace}

\usepackage[maxcitenames=5, citestyle=authoryear-ibid, style=authoryear, autocite=footnote, maxbibnames=99]{biblatex}
\DefineBibliographyStrings{german}{
  andothers = {et al}
}

\DefineBibliographyStrings{ngerman}{
   andothers = {{et\,al\adddot}},
}

\renewcommand{\thesection}{\Alph{section}}
\renewcommand{\thesubsection}{\Roman{subsection}}
\renewcommand{\thesubsubsection}{\arabic{subsubsection}}

\RedeclareSectionCommand[%
  beforeskip=-0.5\baselineskip,
  afterskip=0.5\baselineskip,
  tocindent=7em,
  tocnumwidth=2.1em
]{paragraph}

\RedeclareSectionCommand[%
  beforeskip=-0.25\baselineskip,
  afterskip=0.25\baselineskip,
  indent=0pt,
  tocindent=9.2em,
  tocnumwidth=3em
]{subparagraph}
 
\DeclareNewSectionCommand[%
  style=section,
  level=\numexpr\subparagraphnumdepth+1\relax,
  counterwithin=subparagraph,
  beforeskip=-0.25\baselineskip,
  afterskip=0.25\baselineskip,
  indent=0pt,
  tocindent=9.2em,
  tocnumwidth=3em
]{subsubparagraph}

\setcounter{secnumdepth}{\subsubparagraphnumdepth}
\setcounter{tocdepth}{\subsubparagraphtocdepth}

\usepackage[automark,headsepline,markcase=noupper]{scrlayer-scrpage}
\clearmainofpairofpagestyles
\ihead{\leftmark}
\ohead{\pagemark}
\setkomafont{pageheadfoot}{\normalfont\normalcolor}
\usepackage{hyperref}
\urlstyle{same}

\begin{document}
\tableofcontents
\section{A}
\subsection{B}
\paragraph{C}
\subparagraph{D}
\subsubparagraph{E}
\end{document}