There are 2 repositories under three-finger-drag topic.
Three-finger-drag support for libinput
Three Finger Drag feature for Windows precision touchpads.
Three-finger drag for Windows Precision Touchpads via SendInput and RawInput
Enable three-finger drag for Precision Touchapds on Windows.
AUR of https://github.com/marsqing/libinput-three-finger-drag, three-finger-drag feature for Archlinux