Best way to create a Large Map or Smaller Connected Maps?

I have a question and I am trying to figure out the best way to go about this and so far all I can think of is either learning to use Level Streaming or perhaps one large open world map?

I wanted to ask because I thought maybe someone here with more experience might know the best way to go about it.

What I am trying to do is build up a nice map or a few maps for a Multiplayer FPS Game that has endless Enemy Waves.

I have two concerns though.

(1) I want to make a level to be large enough so that the player(s) have enough room to stand a decent chance but then I wonder if I make it too large will there be too much room and it be boring unless I fill the map in a lot somehow.

(2) This is something I am struggling to figure out is proper map size scaling so I have just been basing it off of what looks good based on the default ue4 character as of right now so I wasn’t sure if there’s a better way or not other than preference and game type.

Looking at other games I have played in the past it looks like Level Streaming is used with separate level areas and maps loaded? I can’t quite tell so I’m not exactly sure.

I really like how Hunt: Showdown does it with Playable Sections on a huge map at random or even how Battlefield 1 does it with the Operations Mode going through a few maps that I assume are one big map the same probably. That is kinda what I would like to do but I wasn’t sure how to create something similar with random areas.

Does anyone have advice on this or a good starting suggestion for someone that is an intermediate level? I’m pretty terrible at blueprinting so I just need to create something that looks good that I can actually achieve one way or another…

Thank you in advance.