So answering my question, the default GOS keyboard is not able to manage Polish language in the way I want it.
My only solution is installation of additional keyboard, but the sole step in not enough.
I also need to download Polish dictionary and I think that is the key.
Maybe if GOS was able to download additional dictionaries I would be able to use default keyboard with them.
Probably I am wrong, but it is shame that I can not download dictionaries which will work with default keyboard for autocorrection purposes. I hope with time GOS devs solve this problem.