RTS Game Assets / Objects. Best approach?

Hello there,

I am making my own RTS genre game. Recently I was wondering about something. I am planning on adding a level editor in the game and I want to easily load up all the assets to the assets list. I was thinking what is the best way in making assets? What I mean is I want to easily add new objects in the game (like new units, environment objects, props and so on..) without having to connect everything together everytime. I know this sounds strange.. I was thinking about using scriptable objects. I also thought in adding prefebs in resources folder and then load all the assets from that folder in the game. But it doesn't seems safe to me this approach so I'm not sure about this. Also all these different gameObjects will have their own various components attached. Are there any better ways in making something like this? How do these other games like Warcraft 3 for example makes something like this?

Any help is greatly appreciated
Thank you!