I don’t have any skill for creating Grant Theft Auto mods, so I release this idea into the atmosphere:
Replace the main character’s model with that of a white cop in uniform. (Don’t worry too much about how this may clash with the game’s dialogue or voice acting.)
Modify the AI of all law-enforcement NPCs such that they always consider the player an ally.
This remains true even as the player’s violent activity summons — per the game’s unmodified rules — growing numbers of patrol cars and, eventually, military-style armored vehicles. The increasingly desperate police within show only unfailing loyalty to the player, no matter how obvious their on-screen crimes become. Consequently, the player faces little consequence for their actions, the (quickly suppressed) retribution of civilians notwithstanding.
That’s pretty much it. Feel free to run with it. I have, as I say, no knowledge for how to make these things, and I’ll be working on something else today anyway.