360° Bulge 4D is in the Distortion category of Alex4D 360° Effects:
Here is what the Final Cut Pro 360° viewer and the viewer look like when the 360° Bulge 4D effect is applied:
Amount controls how much the clip is distorted.
Radius and Centre controls the size and position of the distortion, which can also be set using the on-screen control.
This effect can work across large areas, but if you make Radius larger than the height of the clip, the effect will not distort the 360° sphere correctly. To see when the distortion is too extreme, turn on Overlays. The colours used in the grid overlay can be changed the Horizon Colour and Grid Colour parameters.