People being interrogated by the police all know that it is about guarding the "statement boundary."

The essence of interrogation is to exploit information asymmetry, and counter-interrogation is not about confrontation or explanation, but only about stating the facts you can confirm.
First, decompose the problem premise, and do not be led into the other party's narrative framework, such as directly denying the premise of hypothetical questions, only returning to known facts;
Second, guard the inference boundary, refuse any guesses or explanations, only speak of what you have seen and heard firsthand, avoiding letting guesses mix into factual records;
Third, see through the "moral stepping stones," where the other party uses understanding and tolerance to guide you into admission, which is essentially a trap for bargaining, but interrogators cannot promise the outcome, so they must refuse to agree at the cost of "cooperation."
Finally, it must be clear that remaining silent and requesting a lawyer present are legal rights, not resistance.
Ultimately, the key is a way of thinking: strictly distinguish facts from guesses, only be responsible for facts, and do not participate in leading narratives.