Nikon Z9 Mirrorless Camera - Manual (Page 633)

633 A Custom Settings: Fine-Tuning Camera Settings
Pitch
D The Virtual Horizon Display
Note that the display may not be accurate when the camera is tilted at a
sharp angle forward or back. The camera will not display pitch and roll
indicators when held at angles at which tilt cannot be measured.
Option
Camera tilted forward Camera tilted back
[ Type A ]
[ Type B ]