Copy the zzz_cheat.pak file to the game folder:

steamappscommonKingdomComeDeliveranceData or C:GamesKingdom Come DeliveranceData

Launch the game with the -devmode parameter.

To do this, make a Windows shortcut to KingdomCome.exe and add -devmode to the end of the Target field.

Example: C:GamesKingdom Come DeliveranceBinWin64KingdomCome.exe" -devmode

cheat_add_item id:XXX where XXX item id