Hi g2gsofast!
I hope you don't mind me adding in my 2 cents

Police brutality is a great idea, but I believe it's important to really think about your position before you leap ahead with your introduction/writing. For example, the topic itself already indicates which POV you'll take - brutality in ANY situation is bad (police brutality, animal brutality, human brutality). It's a bit too simplistic and obvious just to argue that 'police brutality is bad' (as meganrobyn mentioned above). The obvious answer is that police need to stop being so brutal. So, how can you move beyond this and offer a more insightful contention?
Here are a few more specific contentions you could take:
Police need to take responsibility for police brutality
There needs to be repercussions for police who behave brutally
Police brutality harms mental health
Police brutality exists because of racism
In terms of the structure:
Introduction - the one suggested earlier sounds great, just make sure you really deliver it during your speech through tone and body language!
1st body paragraph (only a few sentences) - explain the what police brutality is, and why it’s an issue. I know that it might seem SUPER obvious, but reality is, everyone will need a brush up. People might’ve ‘heard’ about police brutality, but not know exactly what it means. If you clarify and define this, it’ll help ensure everyone is on board with what you’re saying, so you don’t lose your audience as you speak. The best speakers are the ones that are engaging, and the only way to stay engaging is to discuss a topic that they understand.
2nd body paragraph - argument 1
3rd body paragraph - argument 2
4rd body paragraph - argument 3
Conclusion - revisit the situation you began with in your introduction. Perhaps you could rewrite the scenario, potentially a different world where police brutality doesn’t exist. You could focus on how people feel safe and don’t live in a world of fear! To cycle back to the idea you start with is a fantastic way to wrap up your oral 😄
Best of luck, and I hope that helps!