I have autocomplete successfully working in auctex. It also works for included packages, so if I, for example, have \usepackage{url} in my preamble, I will get autocompletion while typing \url.
However, this is not the case for the physics package in latex.
One possible problem I can think of is that this package makes use of xparse, so there is no \def or \newcommand in physics.sty but instead commands like \DeclareDocumentCommand.
Is there a way to get autocomplete for physics.sty?
