What I want to know is how did the event end? Did the crowd just spontaneously disperse after a few hours or did police force push them back? And what police, since there were relatively few there?
Having seen many videos of J6, I would say that the police did not push the masses of the people back. There were few, if any, arrests that day.
The people just dispersed, many of whom had walked through the Capitol rotunda taking selfies and pictures of that beautiful architectural space. They stayed between the velvet ropes after walking in the open doors and walked out. Since then they’re being treated like criminals.
It is my guess that the vast majority of the people who walked into the Capitol and out had never been in that building before because few Americans have. Many of them may have never even been to Washington DC before. After attending what was basically a Trump rally with about 200,000 at the Ellipse, marching together with other MAGA supporters to the Capitol, they had to have been feeling very happy. Days, weeks or months later when the FBI came to arrest them, their world came crashing down.
The whole day was not organized by Trump. Trump was invited to speak at an event organized by IIRC, Women for Trump. If Trump had organized it, it would probably been much more under control.