I'm looking for small Type-C Male to 2x Type-C Female cable for smartphone (with the possibility of charging). But I really haven't even seen any. Is there an opportunity to find any, do they exist?
I think what you are looking for is called "USB Type-C splitter".
It seems that those things do exist, they are just not common yet and I'm not sure if you would be able to use both of the ports for data transmission, but at least you should be able to listen to music over type-c headphones and charge at the same time, as per the item description.