This is probably unrelated to 2D, since you are basically looking for random map generation, which would work for 2d and 3d in similar ways… at least the principle behind the scenes.
Here is one of probably many solutions for this:
This should give you a starting point. After this runs, you can decide, how to connect the results from this generator to your tilemap to procude the world. Or maybe its easier to make it in 3d and just set up the camera to a top-down view, that almost looks 2D (in perspective view, since orthogonal still have serious problems with lighting).
And if you google for random map generation, you most likely can find several more ideas about how to solve this 