Look at the Documentation for “Procedural Foliage Volume”. That sounds very much what you’re looking for. Although, due to them making use of hardware instancing they won’t be affected by occlusion culling. (Which is the term used for when the engine stops rendering whatever isn’t visible to the camera.) But that’s okay, because the performance savings of using hardware instancing will be more beneficial than if they were to be culled anyway.
As long as you set up the LODs wisely, you’ll be perfectly fine