How to do “new game +”

After you complete the campaign there’s sometimes a opportunity to do a harder version.
You can somewhat replicate the difficulty by using a mod that increases the difficulty from 1player difficulty to 2player and so on ( valheim has a system that increases difficulty based on the amount of players present ) and downloading a bunch of mods that add new enemies and bosses, and by downloading the epic loot mod you are given a better opportunity to kill those enemies.

I recommend that you keep your original world mod free and on the new world have all the mods downloaded. This makes your original world safe from corruption when the next update comes out (like the mistlands) however you will have to regrind the rarities.

TLDR: make a new world with only mods in it, you want epic loot mostly and a mod that increases difficulty and a mod that adds new enemies