If the RigidBody2D was already in the scene you can’t teleport it like that because it will be only teleported for a frame and the next frame the physics system will teleport it back to whatever position it was originally.
You’ll need to do it in RigidBody2D._integrate_forces() and modify the state.transform.origin accordingly. You can check this answer How can I change a node's position during physics interpolation without fast moving effect? - #2 by mrcdk as to how to do it