Super flat customization

The super flat but if you choose custom you can change the layers and more such as blocks in the x and y axis instead of only the z and for a custom amount of chunks squared and able to have multiple of these areas then put them together randomly using the seed unless specified that certain areas can't touch which then other areas would be in between two others (only works for 3 or more areas) this would allow for worlds of customization (literally) letting anyone to make their own cool world and maybe allow the option for a normal non super flat world layer where it is like a normal world but at a certain z axis or if an area is set for it instead you can make a custom structure with you decision on rarity this could be used for stuff like sky islands or an hanging world under bedrock or an backroom like area or an very large sea with only mountains reaching out of the water creating islands or an infinite parkour map with levels like the popular "parkour civilization" videos by evbo