Hi!
I’m working on an Architectural scene right now … trying to improve the look of the foliage.
The lighting consists of a Directional Light (Stationary, 20lux, and Cascade Shadow Maps), a Sky Light (Intensity of 1, Captured Scene and Stationary too, because the Cascade Shadow looks a lot better). Additionally there is a HeightFog and Volumetric Clouds, but I don’t assume they contribute a lot to the rendering process. Foliage outside is a mix of grass, bushes and trees out of Forester and some grass-assets are from Megascans library. So there is a little bit of work to do with the materials. The whole foliage itself is Movable, so no light is build for them. (Too high and too complex Lightmaps are the reason, I think? Or am I wrong with this?)
My main problem, beside the poorly material setup for the foliage, are the shadows in the scene. Especially with the bushes that are actually inside the sadow of the trees …
And also the three trees, all the same, are looking different. The one on the left looks like it has some shadow on itself, but the other ones are nearly looking Unlit.
I tried DFAO, but that isn’t working the way I want and also brings up a lot of issues with the whole Interior of the building. Raytracing isn’t an option either, because a VR application is needed.
The question would be, if you, lovely visitor of this thread, look at the images: What could be totally wrong? It is my first real approach on the Exterior and I’m kind of stuck right now. I somehow like the results so far with the grass, but since all the other foliage is placed the whole scene turns bad 
If I missed some important informations about the setup, I’d love to deliver more of it! But for now …!
All the best!