Is Blender suitable to make the level design for an RPG? Sadly, the Unity level designer isn’t available right now.
Hi,
Answer is: Anything is suitable. I use 3ds Max to create detailed cave rooms with objects built in to one object. And this workflow is great for texture baking too. Watch out for texture sizes though, if you make one huge texture for each scene then your project will rise in size dramatically.
You can use Blender. 
Yep. The guys above my post are right.
And with time and patience, you’ll make some nice levels.