I managed to insert a row with custom font series and font color.
\documentclass{article}
\usepackage{tabu}
\usepackage{xcolor}
\begin{document}
\begin{tabu}{ l | l l l l }
\rowfont{\leavevmode\color{red}\bfseries}
A & 1 & 2 & 3 & 4 \\
\hline
1 & A & B & C & D \\
2 & A & B & C & D \\
3 & A & B & C & D \\
4 & A & B & C & D \\
\end{tabu}
\end{document}
How can I additionally change the background colour of the row e.g. to black? I experimented with \rowcolor but it returns an error. Perhaps this can be achieved with tabulx?



nicematrixortabularraypackages. If you only need a few cells colord,colortblmight already be enough. You might want to look at the other solutions provided here https://tex.stackexchange.com/q/26360/47927 (where your code example probably also originates from). – Jasper Habicht Jun 07 '23 at 08:20