You can change the skip before the heading of a chapter by eg.
\RedeclareSectionCommand[beforeskip=\dimexpr5cm-\headsep\relax]{chapter}
If this change should only affect ToC, LoF, LoT and other lists under control of package tocbasic you can use it as argument of \BeforeTOCHead.
Unfortunaly there is no bibliography in your MWE. So I guess that you use biblatex:
\documentclass[12pt,bibliography=totoc,listof=totoc]{scrbook}
\newcommand*\specialchapterbeforeskip{%
\RedeclareSectionCommand[beforeskip=\dimexpr5cm-\headsep\relax]{chapter}%
}
\BeforeTOCHead{\specialchapterbeforeskip}
\usepackage{biblatex}
\addbibresource{biblatex-examples.bib}
\defbibheading{bibliography}[\bibname]{\specialchapterbeforeskip\addchap{#1}}
\begin{document}
\tableofcontents
\listoffigures
\listoftables
\part{part}
\chapter{chapter}
\section{section}
\cite{companion}
\begin{figure}
\caption{test}
\label{testfigure}
\end{figure}
\printbibliography
\end{document}



Example with package natbib (see comments below of my answer)
\documentclass[12pt,bibliography=totoc,listof=totoc]{scrbook}
\newcommand*\specialchapterbeforeskip{%
\RedeclareSectionCommand[beforeskip=\dimexpr5cm-\headsep\relax]{chapter}%
}
\BeforeTOCHead{\specialchapterbeforeskip}
\usepackage{natbib}
\bibliographystyle{plainnat}
\renewcommand\bibsection{%
\specialchapterbeforeskip
\addchap{\bibname}%
\markright{\bibname}%
}
\begin{document}
\tableofcontents
\listoffigures
\listoftables
\part{part}
\chapter{chapter}
\section{section}
\cite{companion}
\begin{figure}
\caption{test}
\label{testfigure}
\end{figure}
\bibliography{biblatex-examples}
First bibliography page
\clearpage
Second bibliography page
\clearpage
Third bibliography page
\end{document}
Result:

You can also patch \chapterheadstartvskip:
\documentclass[12pt,bibliography=totoc,listof=totoc]{scrbook}
\usepackage{xpatch}
\makeatletter
\xpatchcmd\chapterheadstartvskip
{\@tempskipa}
{\ifspecialchapter 5cm \else \@tempskipa\fi}
{}{\chapterheadstartvskipPatchFailed}
\makeatother
\newif\ifspecialchapter
\BeforeTOCHead{\specialchaptertrue}
\usepackage{natbib}
\bibliographystyle{plainnat}
\xpretocmd\bibsection{\specialchaptertrue}{}{\bibsectionPatchFailed}
\begin{document}
\tableofcontents
\listoffigures
\listoftables
\part{part}
\chapter{chapter}
\section{section}
\cite{companion}
\begin{figure}
\caption{test}
\label{testfigure}
\end{figure}
\bibliography{biblatex-examples}
First bibliography page
\clearpage
Second bibliography page
\clearpage
Third bibliography page
\end{document}
Then you can also use to change the space before other chapters, too:
\specialchaptertrue
\chapter{Abstract}
\chapter{Introduction}
\specialchapterfalse
\renewcommand\bibsection{\specialchapterbeforeskip\addchap{\bibname}\markright{\bibname}}works for me. – esdd May 23 '18 at 09:43