A Chord plot is always drawn on a unit circle.

def get_extents(self, element, ranges, range_type='combined'):
        """
        A Chord plot is always drawn on a unit circle.
        """
        xdim, ydim = element.nodes.kdims[:2]
        if range_type not in ('combined', 'data', 'extents'):
            return xdim.range[0], ydim.range[0], xdim.range[1], ydim.range[1]
        no_labels = (element.nodes.get_dimension(self.label_index) is None and
                     self.labels is None)
        rng = 1.1 if no_labels else 1.4
        x0, x1 = max_range([xdim.range, (-rng, rng)])
        y0, y1 = max_range([ydim.range, (-rng, rng)])
        return (x0, y0, x1, y1)