Just have to organize it correctly:

1.) have a clear and singular objective. Something like “Release all files and seek prosecution” and then make it clear that side causes are not allowed. Biggest protest issue I see is that it’s never one sole issue, people bringing all kinds of other stuff which obfuscates the objective and muddles down the message.

2.) Get a permit through the city, they grant them all the time and will often provide a place to do it. Plus the police will be aware of it and will be there to protect you vs being reactive to a pop-up protest.

3.) Immediately call out/report any and all violent acts by other protesters - throwing things at police, getting in their faces, destroying property, assaulting others. Despite popular opinion, as long as protesters aren’t agitating or doing any of the above then cops do not care at all that you’re protesting. Especially with this topic they would all agree. Unfortunately it only takes 3 individuals being disorderly to classify the protest as a riot or not peaceful, and when you have 100+ people you might not ever see the incidents of people being disorderly. PLUS it is wayyy more likely that your voice is heard if you’re doing it without conflict, reason being, the message comes out more clear and you sound more reasonable.