This amazing data pack can generate a terrain.
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It has 8 biomes: Forest, Desert, Taiga, Snowy, Badlands, Jungle, Savanna, Custom. Each biome has an area of 3x3 chunk.
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How to use this data pack?

First, you have to give your selft the terrain eggs. Type "/function #minecraft:give-terrain-eggs"
Next place the eggs down then type "/function #minecraft:spawn-terrain"

P/S: If you want the terrains to link together, you must generate it simultaneously.

*Watch the tutorial on Youtube: youtu.be/Nmy-1PKYvmQ
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To install this data pack, copy the folder that you downloaded and paste it into the data pack folder located in your world folder. Then, all you have to do is type: "/reload"
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Have fun! :-)