Hi, two things:
(-) If you use a procedural foliage spawner to spawn meshes, then you can set a start and end cull distance there (that is likely why the trees are getting culled). You can change the cull distance in the procedural foliage asset.
(-) As for the landscape components, that is likely coming from world partition. If you don’t run as server and have world partition enabled for the map (default in ue5), then by default world partition will cull things based on distance. I never really used world partition, so don’t really know how to change the culling there, but you could check the world settings under World Partition Setup or do an online search for that.
And the culling does not happen based on where the player start or world origin is, but based on where the player camera is.
Generally speaking, if you create a larger map, then you will likely need some kind of streaming system + hlods for it to run performant (so in the beginning you could just ramp up the cull distance, but eventually rendering everything till infinity will likely perform (much) worse than culling things on distance and replace them by merged simplified meshes).