I have heard once, that voice guide is supposed to be able to read subtitles on Samsung TVs. However, I wasn’t able, to make it work. Neither in Netflix nor in any other app.

It sounds like what you are looking for is audio description. If you used voice guide it would just read the words that they were reading out loud already which wouldn’t be helpful. If you turn on audio description, the describer would read the subtitles in the language you picked for movies where subtitles are needed for translation purposes. To turn them on, change the language within the app (on Netflix or Hulu) to English Audio Described which can be done with Voice Guide for shows that have description.