Hi, my advise: use modular assets and place them inside the UE4 editor. There is already a ton of free assets on the marketplace and as unreal engine user you’ve also got free access to the whole quixel megascans library for use withing unreal engine.
And I would suggest you start with a landscape: https://docs.unrealengine.com/en-US/…art/index.html
When placing assets inside the UE editor you can place them by hand, or use the foliage tools for procedural placement
You can also use splines to place something like fences, or roads
And of course there is always editor scripting for custom things that you don’t want to place by hand.
And you can organize the assets you’ve placed into the world by creating folders.
And as an advise: Just try out different ways and don’t spend too much time creating assets in blender or creating your map (trying to make it whole or trying to get it perfect, better spend the time trying/learning new workflows since that will enable you to create your assets/maps much faster and more optimized). You will learn as go (especially if you watch many tutorials) and as time goes on you will be able to create much more optimized assets and maps, and will therefore discard most of the stuff you will build now (I actually discarded them several times, so discarded them once, created new once, discarded those, and so on… :)).
So I can tell that from my own experience. Today I don’t use anything I’ve created in my first couple of months and I periodically overhauled (essentially rewrote) all my code.