[read] up (on|about) {sth}

to extensively read on a specific topic to gain more knowledge or understanding

To better understand the economic theories discussed in class, I spent hours reading up on the subject in the library.
She read up about ancient civilizations to write a comprehensive history paper for her college course.
To prepare for the job interview, she read up on the company's background and recent achievements.
In his free time, he enjoys reading up about space exploration and the mysteries of the universe.
Before traveling to Japan, I decided to read up on the country's history and culture to make the most of my trip.