Nikon Z9 Mirrorless Camera - Manual (Page 630)

630 A Custom Settings: Fine-Tuning Camera Settings
Select [ OFF ] to hide the white border around the shooting displays in
the monitor and viewfinder.
Choose a framing grid for the shooting display. The selected grid can be
displayed by placing a check (
M ) next to b in the list for Custom Setting
d17 [ Custom monitor shooting display ] ( 0 634) or d18 [ Custom
viewfinder shooting display ] ( 0 636).
d14: Image Frame
G button
U A Custom Settings menu
d15: Grid Type
G button
U A Custom Settings menu