This is a setting hack that can be enabled on the "Settings" page of the Mods List.
This hack adds a free camera mode and a no clip mode to the game.
Free Camera Mode
Free Camera mode hides your character/car and gives you free control of the camera.
Exiting this mode will return you to where you were when you entered it, restoring what regions were loaded at that time as well as which ped and traffic groups were in use.
No Clip Mode
No Clip mode moves your character/car around freely.
Exiting this mode will drop your character/car wherever you moved them to.
Settings
Keybinds
Toggle Free Camera
The key used to toggle Free Camera mode.
Defaults to O.
Toggle No Clip
The key used to toggle No Clip mode.
Defaults to P.
Move Forward / Move Forward (Alt)
The key(s) used to move forward while in either mode.
Defaults to W and Up Arrow respectively.
Move Backward / Move Backward (Alt)
The key(s) used to move backward while in either mode.
Defaults to S and Down Arrow respectively.
Move Left / Move Left (Alt)
The key(s) used to move left while in either mode.
Defaults to A and Left Arrow respectively.
Move Right / Move Right (Alt)
The key(s) used to move right while in either mode.
Defaults to D and Right Arrow respectively.
Move Up
The key used to move up while in either mode.
Defaults to Page Up.
Move Down
The key used to move down while in either mode.
Defaults to Page Down.
Rotate Z (Roll)
The key used to roll the camera in either mode.
Defaults to Z.
Configuration
Speed Move / Rotate / Zoom
Sets the movement, rotation and zoom speeds of the camera in either mode.
Defaults to 1.
Invert Horizontal Rotation While Upside Down
Inverts the horizontal rotation of the camera while it is upside down in either mode.
Defaults to Enabled.
Rotation Respects Roll
Makes the rotation of the camera respect its roll.
Defaults to Enabled.
Notes
While not currently configurable, you can also zoom the camera in and out using the scroll wheel.