In other words, he could move an existing cabinet officer to the Department of Justice without further hearings, instantly making that person the Attorney General.

Do you have a link by any chance?

https://www.voanews.com/a/jeff-sessions-three-options-donald-trump-replacement/3962546.html

A second option is to circumvent the department's normal succession plan altogether and make an interim appointment under the Vacancies Reform Act of 1998.

The little-known law allows the president to appoint acting heads of departments for up to 210 days when the incumbent resigns or is unable to perform his duties. In the case of the attorney general, there is a caveat: The candidate must be a Senate-confirmed official and cannot be asked to fill the position permanently.

In theory, Trump could look outside the Department of Justice for a successor to Sessions. However, his choices would be limited to the 50 or so of his appointees the Senate has so far confirmed.

Nevertheless, Yeomans said, the Vacancies Reform Act "would allow him to shop around for someone who is more sympathetic to his views."

There is another wrinkle: While Trump can make an interim appointment if Sessions resigns, it is less clear he can do so if Sessions is fired.