I already suggested you do the tutorials and the help file to learn about the engine, because the engine is too much to "learn by doing".
That way you also might have learned about the sample maps included in the program...
There's the question you're asking and the question I think you want.
Yes, the map is stored in a file, you could download an entire map.
No, you generally do not find maps available to download. Maps are a huge part of what actually makes your game - what would be the point of you saying you made a game if your towns or dungeons or whatever are the same as someone else's?
Many tilesets that you purchase will include more sample maps so that you can see how to use the various pieces of that tileset well.
Aside from that, you're talking about hiring other people to draw your maps for you.
I typically ask this on my normal social media channels, but figured there may be good replies here. Anyone got any good horror movie recommendations? I've seen a lot, but I always love getting suggestions! Bonus points if you know which service it is streaming on (in the US) - bring on the spOoooOky!