Miller offers the advice of experts not to confront the harasser in the moment (I assume she means in circumstances where the victim is not in peril), and instead suggests a variety of tactics:
• Distract the harasser: The bystander can address the victim directly and pull them out of the situation.
• Confront the harasser: Reflect on what you saw and ask them about it.
• Check in with the victim: Ask how they are and make sure they know they did nothing wrong.