In vanilla Minecraft, you can extensively customize a new world, such as changing ore spawn rates and so on, by choosing Customized terrain during world generation.
I bought a Realm yesterday and am wondering about my ability to use the Customized terrain for the individual worlds I create as administrator of the Realm. Is it possible to configure the presets of a world on a Realms server?
I know that it is possible to upload an existing single player map to a Realm, as seen in this answer here: Can you turn a single player world into a Realm server? Would this work perfectly, or would the ore spawn ratios return to normal once you generated new terrain? Also, can you choose the other presets that are given in vanilla Minecraft, such as Caver's Delight, Water World, etc?
Best Answer
I just tested this and can confirm that uploaded worlds (as per the answer linked in the question) preserve the configurations and new terrain will generate as expected.
The reason this works is because the customization options (the long string that is generated) are saved within the NBT data of the world itself (level.dat), under the
generatorNameandgeneratorOptionstags.