Buyable cop car.

[damion.ord]

Cos I love RP-ing Robocop when responding to NCPD gigs and finding abandoned cop cars isn't easy.

[Silverbane7]

Unless they changed it, there is a cop car out at BioTechnica flats that does not despawn.
Its part of one of the hidden gems, some border patrol members who got flatlined.
Find the furthest entrance and head to your left along the wall and you should find them.

Or, you could use mods.
https://www.nexusmods.com/cyberpunk2077/mods/9935
Police NCPD fullpack cars. Uses TweekXL to allow you to spawn and then summon your own police cars.

https://www.nexusmods.com/cyberpunk2077/mods/12130
NCPD V wardrobe. Customisable police clothing, armour (cosmetic) and gear (note: requires phantom liberty)

https://www.nexusmods.com/cyberpunk2077/mods/7605
MONSTERiader NCPD set. Similar to the above, but is older and does not require phantom liberty.

You might also like the ErebusArms 'Linothorax' Advanced cooling system suit.
https://www.nexusmods.com/cyberpunk2077/mods/11977
It is a Netrunner suit, but it looks more like the anime combat skintight armour and cyborg skin suits
(You mentioned RoboCop)
Add to that the 'modular military accessories' pack and 'military vest' from ScorpionTank here
https://www.nexusmods.com/cyberpunk2077/users/59377041?tab=user+files
And you should be able to have most of your police fun

Just remember tho, you won't be recognised as an officer by them, unfortunately, so they may still agro on you.

Also, don't forget the legendary police set you can collect (iconic clothing) and the MaxTac gear Judy has (FemV's only, vanilla)