As of my last knowledge update in January 2023, I don't have specific information about JoJo Siwa Be You in a 100ml size. Fragrance offerings, especially those associated with celebrities like JoJo Siwa, can vary, and new products may have been introduced after my last update.

For the most accurate and up-to-date information, I recommend checking the official JoJo Siwa website or contacting authorized fragrance retailers that carry JoJo Siwa products. They can provide details on the latest releases, including Be You and its available sizes.