Useful Commands

restartMapWithLobby
Can be executed by the host to restart the entire map for all players in the party.
exitShellLobby
Can be execute by the host to leave the match and retain all players within their party, so long as the clients do not select ACCEPT in the warning menu.
disconnect
Can be executed by clients to leave the match and stay in the party, so long as the clients do not select ACCEPT in the warning menu.
g_havokHeapLimitMB 200
Can be executed by any player to increase the havok limit (how much geo can do things simultaneously) which may prevent some crashes.
net_maxRate 100
Can be executed by any player to increase the network rate which may decrease latency.

pvp_skipReadyUp 1
Can be executed by the host to bypass the "waiting for players" event on map start. Leaving this enabled with other players may create issues for clients.
pvp_skipReadyUp 0
Can be executed by the host to enable the "waiting for players" event.
ai_faction_overrideEmotion_ai 0
Can be executed by the host to stop all AI from attacking much like the "notarget" command.
ai_faction_overrideEmotion_ai -1
Can be executed by the host to enable normal AI aggression towards players and other AI.
warning_disable allCan be executed by any player to disable the barrage of warnings in the console.
warning_enable all
Can be executed by any player to enable all warnings. Restarting the game will also enable all warnings.

You can input commands as a new line into the candidate.cfg file within the DOOMEternal\base folder to auto-execute them when the game launches. Below is an example of DOOMEternal's installation file path for Windows.
C:\Program Files (x86)\Steam\steamapps\common\DOOMEternal\base\candidate.cfg
The candidate.cfg file can execute other config files with the exec <NameOfFile.cfg> command added as a new line.