In Warzone 3.1 and above, it's possible to enable cheat mode in multiplayer games but it works a bit differently. You have to request cheat mode by pressing Shift + Backspace and then wait for the majority of other players to approve your request.
When a request is made, all players will see a message about the request in their console. To approve the request, they have to press Enter to open their console, then type "cheat on" (without the quotes) and then press Enter again to confirm.
Video of Cheat Mode
This video shows how to enable cheat mode in single player games and use some cheat codes on Warzone 2.3.x and above:
The following shortcuts work when in cheat mode...
Same as Cheat Code...
Shift + Backspace
Toggle "Debug" mode (enable/disable cheats)
Shift + F12
Toggle sensor and weapon range display for selected units or structures.
Yellow fire indicates range of weapons, blue orbs indicate range of sensors.
Ctrl + B
Complete mission (Campaign Mode only)
let me win
Ctrl + E
Toggle gateways display (version 3.1 or above)
Old Warzone versions: Show selected unit info.
Ctrl + G
Reveal entire map, same as having a Satellite Uplink Centre
Ctrl + I
Old versions: Recalculate lighting.
let there be light
Ctrl + J
Toggle fog on/off.
Ctrl + K
Toggle mist on/off.
Ctrl + L
Trace selected droid/structure to debug (useful for developers)
Old Warzone versions: Change fog colour
Ctrl + M
Recent Warzone versions: Toggle unit pathfinding display
Old Warzone versions: Skip mission (Campaign Mode only)
let me win
Ctrl + N
Makes your units stronger and increases weapon damage.