This trailer, in addition to previewing the song, also revealed that the series will premiere April 10th. Check out the ANN article for additional cast/staff information. Synopsis from AniList:
The third season of Kono Subarashii Sekai ni Shukufuku wo!
The dysfunctional party is back, but they may be short a member soon ’cause Kazuma is over it. Disillusioned with adventure, he wants to become a monk, but Aqua, Megumin, and Darkness call bull. However, the career dispute gets put on hold when a princess requests to hear all about their tales. Will the taste of fame at the royal castle keep them together or will this mark their farewell tour?
Volume 6 is my absolute favorite, I’m so glad it’s about to air! What we can see in the trailer already looks really good!