CD Projekt Red said there would eventually be modding tools available but didn't say when, and I can't imagine that these will be a priority given all the issues with the game at the moment.
I know nothing about how this game works, but I have noticed that there's no car chases outside of scripted sequences in the story and the police don't seem to be able to make arrests, drive cars, or do... anything?
I should note though that there is a police uniform in Cyberpunk 2077 that you can obtain in the "Following the River" side mission. If you open your inventory just after picking up the AR goggles and while while the "Trouble in Heywood" logo is on screen, you can drop the uniform given to you for that part of the mission to the ground and then pick it up after that part of the mission finishes. If you don't drop it, the uniform will be taken from you automatically during the mission.