PUBG or Fortnite large map how to Load?

How to load a large map? According to the official, level streaming is used to cut the big map into many sublevels and use distance to display sublevels, but if the player in high sky, all of them are displayed?. if player on ground, the sublevel will cut with distance, but player can see the sub level’s edge.
how anyone studied the pubg or fortnite how to load large map?

Might help, 不用谢~

Plus you might want to look at ProxyLOD and HLOD systems.