John Williams has composed the music for all eight main Star Wars films and it looks like he’s going to help out with Solo: A Star Wars Story. John Powell will compose the vast majority of the score and I’m sure that it will be fantastic. He did, after all, compose the scores for the How to Train Your Dragon films as well as the Bourne movies. However, to have Williams write the main theme for Han Solo is just phenomenal. I love his work and think he’s a fantastic composer. The information comes from an interview with Variety where Williams says:
The fact that Williams is anxious to hear Powell's work just adds to my excitement for this score. Are you excited for Solo? What about the score? With Williams involved, it's hard not to be excited about that.