Dedicated Linux server MaxPlayers not getting configured as expected

We’re trying to change the MaxPlayers count for our dedicated Linux server, which I would assume would be done by setting the following in the DefaultGame.ini:

[/Script/Engine.GameSession]
MaxPlayers=500

However, when we package the server, only the Engine.ini and GameUserSettings.ini are created - Game.ini (and DefaultGame.ini) is nowhere to be seen and the setting is not being updated, leaving the server thinking the default of 16 MaxPlayers (from BaseGame.ini) is set.

How do we get this value - or preferably the whole ini - propagated successfully without editing the Engine’s Base config files and also - preferably - without manually copying the file in to our server distribution?

UE 5.3