It’s possible if you buy high enough capacity servers that can deal with the huge processing time it would need to be able to keep far away distance, in shot without fading. With large maps at current, UE loads them in square by square the closer you get to it - DayZ also use’s draw distance imo. The only difference is, DayZ use’s servers that can load that distance into shot quickly before a player even reaches it.
Fortnite was made using Unreal Engine so the comment about UE not being able to hack large multiplayer games is false. The only thing you would need is a big enough capacity server in order to render fast and also, have high capacity to handle so many players on one map at once.