Originally posted by UltraSmurfBrigade:

Update: I went on the Valheim discord - this method will not work. The only way to add the new content is to use mods. The "Upgrade World" on Nexus mods seems to have this capability.

Or... no need to use mods ;)
Even if, for example, you have a save game that has already uncovered the whole map, you can still explore the new cave content... just world hop ;)
The new world will be completely undiscovered and so the caves may be found and explored. Any loot you find may be carried back to your main map.

Caves will generate on mountains that have NOT been explored. If you've filled out a good portion of your world it might be better to start fresh. If you think there are still a lot of larger mountain ranges left you might be okay. ..but it will probably be a fair distance away.

Short answer. You can find new content in parts of the map you have not visited/still under fog.

Has anyone tested if using console commands to hide the map and then updating would make everything sufficiently "undiscovered?" Or is it tracking some other way?

Update: I went on the Valheim discord - this method will not work. The only way to add the new content is to use mods. The "Upgrade World" on Nexus mods seems to have this capability.