You can't change game options by commands so you have to find the config file.
to access the configs you have to:
1. Find The Hidden addon in your addons folder (steamapps\common\GarrysMod\garrysmod\addons\the_hidden_443458575.gma)
2. Open the file using gmad.exe (steamapps\common\GarrysMod\bin\gmad.exe)
3. It will create folder named "the_hidden_443458575" in Addons folder
4. Open config.lua using notepad (the_hidden_443458575\gamemodes\thehidden\gamemode\config.lua)
5. Done!

Now you can now enable custom mode to change your skill points as Hidden, use different modes for RMB, configure all stats for humans and Hidden etc.