While issues are unlikely, setting Iris as your main world while using other unsupported world generators will cause world corruption. Unsupported plugins and datapacks include: Terra, EpicWorldGenerator, Terralith.
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To replace your main world make sure you have:
server.properties file.server.properties file and find the option containing the level-name parameter.world to the current name of your Iris world.
world folder and copy the folder datapacks. Move this folder into your iris world folder (in this case iris) and paste the folder there.world, world_nether, and world_the_end as they are no longer used.iris_nether and iris_the_end will be created.Once you have finished these steps, you have successfully set Iris as your main world.