What is a word or term for extreme questioning?

browbeat intimidate (someone), typically into doing something, with stern or abusive words.

Google top hit used a witness under cross-examination as the example:

a witness is being browbeaten under cross-examination

Alternative

gaslight to cause (a person) to doubt his or her sanity through the use of psychological manipulation

Usually it involves more than just talking, but talking quickly and sternly, and forcing yes-or-no answers is a form of psychological manipulation; and leading a witness to question their assertions is a doubt to sanity, so it fits.

A possible word would be duress.

https://dictionary.cambridge.org/de/worterbuch/englisch/duress

Interrogation. Extreme questioning.

“The woman was subjected to an interrogation by authorities after she reported a crime.”

“The man was interrogated for hours after the murder weapon was found in his home.”

Grilling is a common informal term in the US. Cambridge:

an occasion when someone is asked a lot of questions for a long time