In the voluntary assumption of risk, a plaintiff must voluntarily consent to the defendant. But it is for the court to bar them from damage judiciously. That is, the recovery of injury suffered in the cause of action.
Here are some actions that are not voluntary:
Suppose the plaintiff gets some assurance of safety, protection, or a remedy. If things finally go south, the plaintiff will not assume the risk of injury. They only assume the risk when the assurance given isn't sufficiently reasonable.
Suppose the plaintiff acted under duress or fear caused by the defendant's act. Then, by law, the defendant owes the plaintiff a legal duty of care not to be easily dismissed.