\documentclass[12pt,listof=numbered,pagesize,bibliography=totocnumbered,oneside]{scrreprt} 

%%%%%%%%%%%%%%%%%%%%% CITATIONS & LANGUAGE

\usepackage[ngerman]{babel} %für die Worttrennung, das Datum, die Bibliographie usw...
\usepackage[utf8]{inputenc} %sonst gibts kein ß usw
\usepackage{csquotes} %sonst beschwert sich Biber

% BIBLIOGRAPHY AND CITATION STYLE
\usepackage[
maxcitenames=3,
backend=biber,
style=apa,
citestyle=authoryear
]{biblatex} %biblatex mit biber laden 
\ExecuteBibliographyOptions{
sorting=nyt, %Sortierung Autor, Titel, Jahr 
bibwarn=true, %Probleme mit den Daten, die Backend betreﬀen anzeigen 
isbn=false, %keine isbn anzeigen 
url=false, %keine url anzeigen 
doi=false
}
\addbibresource{Bib.bib} %Bibliographiedateien laden 

\DeclareLanguageMapping{german}{german-apa}

\DefineBibliographyStrings{german}{ %has to be same as Babel!
   andothers = {{et\,al\adddot}},             
} 
%%%%%%%%%%%%%%%%%%%% FORMAT

%% PAGE DIMENSIONS
\usepackage{geometry} % to change the page dimensions
\geometry{a4paper} % or letterpaper (US) or a5paper or....
\geometry{top=2.5cm, bottom=2.5cm, left=3cm, right=2.5cm} %wie in der Formatvorlage definiert

%% LANDSCAPE
\usepackage{lscape} %\begin{landscape} ... \end{lanscape}

%% FONT
\usepackage{helvet}
\renewcommand\familydefault{\sfdefault}
\usepackage[T1]{fontenc}

% SIZING OF SECTION HEADERS
\setkomafont{chapter}{\LARGE}
\setkomafont{section}{\Large}
\setkomafont{subsection}{\large}
\setkomafont{subsubsection}{\normalsize}
\setkomafont{paragraph}{\normalsize}
\setkomafont{subparagraph}{\normalsize}

%SIZING OF CAPTIONS
\usepackage[font=small]{caption}

% FONT SIZE
\makeatletter 
\renewcommand\LARGE{\@setfontsize\LARGE{16pt}{19}}
\renewcommand\Large{\@setfontsize\Large{14pt}{17}}
\renewcommand\large{\@setfontsize\large{12pt}{15}}
\renewcommand\small{\@setfontsize\small{10pt}{10}}%Abbildungs-,Tabellenbeschriftung und Fußnote
\makeatother

%% SPACE AROUND SECTION HEADERS
\RedeclareSectionCommand[
  beforeskip=.7\baselineskip,afterskip=.3\baselineskip]{chapter}
\RedeclareSectionCommand[
  beforeskip=.7\baselineskip,afterskip=.3\baselineskip]{section}
\RedeclareSectionCommand[
  beforeskip=1\baselineskip,afterskip=.3\baselineskip]{subsection}

%% GENERAL SPACING
\usepackage[onehalfspacing]{setspace}
% \usepackage[doublespacing]{setspace}

%% HEADER AND FOOTER
\usepackage{scrlayer-scrpage}
\lefoot*{TITLE}
\refoot*{Page \pagemark}


%% FRONTPAGE

% DATE
\usepackage[useregional]{datetime2} 

% TABLE (GRAY LINES)
\usepackage[table]{xcolor} 

% PICTURES
\usepackage{graphicx}

% SUBCAPTIONS
\usepackage{subcaption} % make it possible to include more than one captioned figure/table in a single float

% ° 
\usepackage{textcomp} 

% SECOND TOC
\usepackage{titletoc} 
\dottedcontents{section}[4.6em]{}{3pc}{-1pc}
\dottedcontents{subsection}[7.7em]{}{3pc}{-1pc}
\makeatletter
\renewcommand\@dotsep{500}   % default value 4.5
\makeatother

% NICER ARRAYS
\usepackage{array} 

% COMMENT SECTIONS WITH \begin{comment} ...  \end{comment}
\usepackage{comment} 

%%%%%%%%%%%%%%%%% TABLES

\usepackage{multirow}

\renewcommand{\arraystretch}{1.5}

\usepackage{booktabs,ragged2e}

\newcolumntype{P}[1]{>{\RaggedRight\arraybackslash}p{#1}}

%%%%%%%%%%%%%%%% MATH

\usepackage{amsmath} %math stuff
\usepackage{mathtools} %nice looking math stuff

%%%%%%%%%%%%%% REFERENCING

\usepackage{hyperref}

\begin{document}
\startcontents[main]


\input{./Textbausteine/1_Titelblatt}

\input{./Textbausteine/2_Widmung}

\input{./Textbausteine/3_Zusammenfassung}

\newpage

\printcontents[main]{}{0}{}
\addcontentsline{to_c}{chapter}{Inhaltsverzeichnis}
\cleardoubleoddpage

\pagenumbering{arabic}
\setcounter{page}{1}

%%%% CONTENT GOES HERE

%\input{}

\small

\printbibliography

\listoffigures

\listoftables

\input{./Textbausteine/4_Abkuerzungsverzeichnis}
\input{./Textbausteine/5_Anhang_Inhaltsverzeichnis}
\input{./Textbausteine/6_Anhang}

\end{document}