Im looking to recreate an old pack of mine, and I used to use this mod in a particular fashion that I can no longer find.

Previously, in 1.10.2 there was this option:
Sets the fill layers from the island Y Spawn down to the the bottom layer in the void world

I see the config is quite different, and I cannot locate this feature in the new config. Was this feature removed? And if so, is it possible to request its return?

I see now that you can do this with customizing a superflat world in the config, closing.