Start Hitman 3 through your mod manager or directly, depending on the mod and manager's instructions. The mod should now be active.
However, the modding community, particularly on platforms like and GitHub , has created sophisticated tools that function as a unlock-all-weapons mod by manipulating memory or save states. The most famous of these is the "Peacock Project" (a custom server emulator) and various "Unlocker" tools. hitman 3 unlock all weapons mod
The is a double-edged sword.