subtitles

I already did that... Unfortunately, that doesn't seem to affect the Blu-Ray player... It only will do Subtitles off the disc, and this particular disc doesn't have subtitles.

The subtitles do work if the disc has subtitles, but if the disc only has Closed Captions, the Blu-Ray Player will not display them.

I like having subtitles whenever possible. FFXIII-2 had subtitles from the start where FFXIII didn't and had to be placed manually. It would be nice to have default subtitles for a new game.

Unless you have a movie file that has the subtitles already embedded into the file then you won't get subtitles.

How can I check if game (in gamepass) have a polish subtitles ora polish language?

I've been looking at various titles on the Xbox Store and on the Microsoft Store (on PC), I can't seem to find any details listed of the languages available on a game. That seems like a massive oversight. You should head over to https://www.reddit.com/r/xboxinsiders/
and make a suggestion in the Weekly Request thread. This seems like a feature that should be available when purchasing a game digitally.

Every game has it's own settings as Crazy suggested. Just look for them under settings for audio/video or in an options menu. Each game has them for the most part. Best of luck to you!