Question How can I set the Nether as my default spawn world/dimension?

I want my players to spawn and respawn in the Nether. I am using a random spawn plugin that lets you add a random spawn area in your worlds and can prevent players from spawning on certain blocks like cacti, water, or the bedrock ceiling in the Nether; problem is I cannot use it in the Nether because the player’s spawn dimension is in the Overworld by default. How can I change this so a players default spawn dimension/world is the Nether, so the plugin can work?

 

Maybe set the level in server.properties to the nether world?

 

I tried that before. If I set the world name to world_nether, it will ignore that the world was the nether and generate a new overworld map along with world_nether_nether and world_nether_end world folders, because in world_nether folder, there is a DIM1 folder that stores the nether dimension, and the overworld is stored in the region folder