Hey so I am making a mobile game and I have been working with LODs. I get how replacing a mesh with a lower quality one works, but for basically the rest of the map and unnecessary meshes that the player can’t even see; is there a way to make that disappear so the game doesn’t even have to load that until the player is close?
Level streaming or world partition 
But then you have glitches because stuff is being loaded in and out.
You can use soft references to not load in parts of blueprints into memory. But you need to hand load them later on with “Async Load Asset”
Is there a performance or resource issue for your project that you are trying to overcome with meshes loaded? If a mesh is not in view it will not be rendered (most cases) using the automatic visibility culling.
Otherwise you can chop up your levels into smaller levels and use the level streaming volumes to load in sub levels right before they would be seen.