By releasing its requests, the House committee offered a glimpse of the depth of the scrutiny that the companies will face and laid out the lines of investigation. The lawmakers are looking for signs of executives’ intent when they made decisions that harmed competitors, according to a person close to the congressional investigation who spoke on the condition of anonymity because the lawmakers’ plans were private.

The information the committee collects can also feed the other investigations, and help lawmakers more sharply question witnesses under oath in hearings, said William Kovacic, a law professor at George Washington University.

“Those interrogations take on an entirely different tone,” said Mr. Kovacic, a former chairman of the Federal Trade Commission. “This is a significant escalation of the process.”

The inquiries into individual companies are complex; the tech giants span a range of digital markets, including internet search, advertising, e-commerce and social media. And the companies are likely to resist some of the requests, contending they could reveal trade secrets.

The companies will almost certainly try to narrow the scope and reduce the volume of the documents they deliver. But the House investigators have leverage. These are document “requests” but backed by the threat of subpoenas if the companies do not comply.

The communications habits of the individual companies will also play a role in determining how much evidence there is and in what form.

At Amazon, for example, Mr. Bezos writes brief emails to make announcements or delegate, but largely gives feedback and discusses issues in person. He is well known internally for forwarding customer complaints to staffers with just a “?,” leaving teams scrambling to resolve the issue.