multiple tilemaps or one tilemap,which is better for rendering?

firstly im a beginner. i am trying to create 2D proceducal map by using tilemaps (in blueprint). my method is spawn actors which include tilemap and filling them in the actor construction script as i want. One tilemap is about 10-15 width x 25-50 height and their bottom are the same level so i gain different height (with this method, i can make hill, mountain etc.).

My problem is that i have too much actor, and i want to make cave or something like that and i have to use more than 3-4 actor to reach enough widthness for a cave.

I thought that if i use one tilemap for a huge level, it may cause some rendering problem

i really dont know how rendering works, but i think engine will try to load every tile in the actor even if it is too far away from me. And maybe it will not load if there are multiple actors far away from me.

So,
1)Is it okay to spawn 1 actor instead of multiple actors (in terms of rendering) ?

If you have any tips or source for this problem, it helps so much

Probably late by now and I am by no means a pro. But one way to do it is multiple tile maps on lvl streams. So you can load or unload them once off the screen. Makes it way lighter.