You could maybe try this, though I’m not sure if it will work:
func change_parent(node, new_parent):
var old_parent = node.get_parent()
old_parent.remove_child(node)
new_parent.add_child(node)
Though if you just want the sprite to be over the player and other objects, and all the objects are on a single-layer/no-canvas-layer, you may be better off adjusting the Z index of the sprite instead. Setting the Z index to not be relative to the parent (z_as_relative) and then setting the z_index to something really high should make it draw on top of everything with a lower Z index.