$ pacman -Qs polkit
local/polkit 0.119-1
Application development toolkit for controlling system-wide privileges
local/polkit-kde-agent 5.22.0-1 (plasma)
Daemon providing a polkit authentication UI for KDE
local/polkit-qt5 0.113.0-2
A library that allows developers to access PolicyKit API with a nice Qt-style API
Both are installed, as polkit-qt5 requires polkit, and is itself required by kauth and kpmcore.