Don’t.
Expanded answer:
If your actual goal is to become a cop, you will NOT combat human trafficking and the abuse of sex workers. The current justice system does not serve these goals, but instead contributes to the stigma and exploitation of sex workers and conflates human trafficking with consensual but criminalized sexual activities. You alone will not have a meaningful effect on this system. Just a fact.
If your actual goal is to combat human trafficking and the abuse of sex workers, I suggest a job such as working in a homeless shelter, an immigrant resource center, at an LGBT youth center, etc. Do things that are not directly related to sex work but have an effect on those most at risk of experiencing sexualized violence or forced labor of any kind.
But also if you’ve never been a sex worker it’s likely that you’re just using this seemingly noble goal as a way to a feed a savior complex that will ultimately do more harm than good, so re-evaluate your intention and remember that this is not about you.