I have the following line using \draw (see MWE below). I would like to have the line change in color, from red on the right, to blue on the left. Current attempts are adding a fading region rather than changing the color of the line itself.
Note that this solution by percusse offers a solution, using a custom fade, but I'm not sure how to edit it to get the effect I'm looking for. I would ideally like to add an edit to \draw[...] that achieves this effect.
MWE
\documentclass[tikz]{standalone}
\begin{document}
\begin{tikzpicture}
\draw [ultra thick,red] (-19.5,-16) to[out=55,in=228] (-14,-9) to [out=45,in=180] (0,-2) to[out=0,in=135] (14, -9) to[out=315,in=125] (20,-16);
\end{tikzpicture}
\end{document}

left opacityandright opacity? I'm looking for a bit more control thatpath fading=west. Something that controls where the fading/opacity starts – Sid Jul 13 '21 at 10:22