[b e r b]

I think you would need sv_cheats to be set to 1 which I wouldn't recommend as it would allow everyone on your server to access cheat commands. Instead I would install the advanced infinite ammo and godmode plugins (linked below) to achieve the same effect. I also linked adminmenu_custom.txt which you could use to enable/disable them through the admin menu however I haven't tested it myself so I'm not completely sure it will work. Put it in the 'sourcemod/configs' folder.

Advanced Infinite Ammo: https://forums.alliedmods.net/showthread.php?p=1754217

Godmode: https://forums.alliedmods.net/showthread.php?p=2067559