As of my knowledge cutoff in September 2024, the initial download size of Call of Duty: Mobile on mobile devices was around 2 GB to 3 GB. However, please note that this size is subject to change as the game receives updates and new content.
Call of Duty Mobile (CODM) requires a significant amount of storage space due to the high-quality graphics, frequent updates, and additional content such as maps, game modes, and events.