Is it possible to use all branches of Breath Styles if a Demon Slayer can use Breath of the Sun?
It was revealed in the latest chapter of manga


   that Tanjiro is a descendant of the Breath Of The Sun User.


Can Tanjiro use the other Breathing Technique?


   It is not yet revealed in the manga but Breath of the sun is the basis of all the breathing techniques and since the memories of the Breath of the sun users is passed down to the succeeding users we can all assume that he can use the other branches as soon as he completely inherit those memories.