Do I need special pens for bullet journaling?

No, but archival, waterproof, and smudge-resistant ink helps. The Sakura Pigma Micron set is the most-reviewed archival fineliner option here, and the Tombow Fudenosuke brush pens are the go-to for hand-lettering and headers. Budget fineliner multipacks like the Taotree set cover everyday writing and simple layouts at a much lower per-pen cost.