Webshinobu kochō does indeed die in demon slayer:
Her death happens during the infinity castle arc, in chapter 143 of the manga, when she is.
Webshinobu kocho's tragic past fuels her determination to kill demons, showcasing her unique combat style and strong will to seek vengeance.
Webshinobu’s legacy continues to inspire tanjiro kamado and her fellow demon slayers even after her passing.
This article covered shinobu kocho’s backstory, the buildup to her.