For premade maps, you should just be able to use any maps from any other grid-based system like D&D or Pathfinder.
There are a lot of example items already in the core rules under “special equipment” but there’s a few more on the wiki (the link for which should be in a purple box at the top of this page).
The wiki also has a few NPCs, and there’s a Fantasy Bestiary on DriveThruRPG which was made by a community member. The excellent Heromuster site also has a random NPC generator that can help you with ideas. The quick-build system in the core rules is really super easy with some practice though, it takes me less than 5 minutes to put together an encounter with 2-4 unique enemy types starting with just an idea.
As for animals, we generally don’t bother statting them up for Open Legend unless they’re meant to be a combat encounter, because Every Roll Matters and if your level 1 character can’t kill a bird without expending a lot of effort then something has gone wrong