Is it possible to initiate a call through Apple Watch in Watch OS 2.0?
Apple watch initiate call
Press the side button on the watch to bring up Friends. Select a friend and at the bottom of the screen you have options to message, call or touch (if your friend has an Apple Watch).
If you're specifically referring to how to initate a call from your apple watch app code. Check out the Phone Links URL scheme reference that is now avalible is watchOS 2.0
Yes it is but the tel: URL scheme is currently broken on watchOS 2 beta 1.