Look for mutual aid organizations. Note that in some US states they are legally gray and will get harassed by law enforcement when they're recognized for what they are.
Or, you can look around your neighborhood for a thing that needs to be done (say cleaning up trash or repairing a playground) and do that thing without asking anyone. Not only will the thing get done, but people will see and become curious, maybe feel better or become inspired.
This sort of activity is the height of radical and punk these days (and can get you in trouble with the law).