I built a neighborhood on small map and now I am running out of space. I'd like to find empty map to add space for my growing community. There are some mentions that usual maps can be turned to shopping districts but not any what already is or how to do it.

I might be misunderstanding you, but you just make a custom shopping district:


And choose a map template:


Is this what you meant, or something else?

Thanks, I didn't know that.

I had to download something from here to be able to create a custom shopping district without having to use the default one first which was always a big problem in my old games.I've used THIS to fix the selection of shopping and downtown districts so activating the default downtown or shopping district is no longer needed before selecting an empty terrain as your shopping district or downtown.