How to change the height/alignment of specific letters – gender specific typography

Define it's function as a new unicode character:

\documentclass{article}

\usepackage{newunicodechar,graphicx}

\newunicodechar{¿}{\rotatebox[origin=c]{180}{?}}

\begin{document}

Verbraucher¿nnen

\end{document}

You can define \? for the purpose. The proposed macro raises the inverted question mark and rescales it to have the same height as an “i”. The dot is slightly smaller, though.

\documentclass{article}
\usepackage{graphicx}

\DeclareRobustCommand\?{%
  \resizebox{!}{\fontcharht\font`i}{\raisebox{\depth}{¿}}%
}

\begin{document}

Verbraucher\?nnen

\end{document}

With stackengine.

\documentclass{article}
\usepackage{stackengine}
\DeclareRobustCommand\?{\abovebaseline[0pt]{¿}}
\begin{document}
Verbraucher\?nnen
\end{document}