He is not a cop, he becomes a cop after he graduates, despite a heavily recurring theme of the books being how corrupt, incompetent, and unjust the Wizarding government and judicial system is.
Rowling never really seems to connect the dots and think, “Hmm, maybe the Aurors are part of the problem,” very much a “cops good no notes” mindset for some reason.
If you want to give her the benefit of the doubt you can assume she thinks Harry will be a reformer, but, also, in the books she never really seems to think anything but the status quo is good so probably not.
TBF I read the books too long ago to remember well what was the state of the depicted society except for an obvious negligence for student safety. In part it’s because I wasn’t old enough to notice that.
I think it did feel “govt bad cops good” at that point and I didn’t think about the government and cops being parts of the same system 😅
I mean the cops are also doing the bidding of the obviously corrupt minister, with the exception of Kingsley Shaklebolt, who is an undercover agent of Dumbledore.
The entire concept of “fighting dark magicians hurr durr” is never put in the context of how subverted or openly on the side of dark magicians the ministry of magic is. Sometimes it is hinted at, like how Arthur Weasley is dissapointed that the department for the missuse of muggle artifacts is chronically underfunded and wizards that like to play harsh pranks and torture muggles aren’t punished properly.