Peacock Patcher is if your new to hitman3/woa modding and want it to be easier to mod and unlock items/add custom items.
Peacock only works for Steam and Epic so hitman 3 on Game Pass is not supported. Since you will be connecting to the peacock servers you must own the game and if it detects you pirated the game you will be banned from the peacock servers.

This is not IOI modding this is a new server patch for hitman.
Which means anything online will not be saved to your IOI account, which means you can't get banned but you can screw up your main save.

Benefits of using Peacock include:
Obtain all unlocks immediately
Play custom or otherwise discontinued/ time limited content such as Ghost Mode, legacy escalations, elusive targets.
Access Hitman's rating system without being connected to IOI's servers

If you need help check the how to run file in the zip.