In many drones, the pitch of the gimbal has a 90° arc of movement: horizontal to looking straight down, 0°--90°: a 90° arc of travel. By allowing upwards rotation, the gimbal has an increased range of pitch movement, with my mavic 2 zoom it becomes +30° to -90°: a 120° arc of travel.
+30° being ideal maximum for keeping the spinning props out of frame.