WASHINGTON—The Justice Department official expected to lead an antitrust investigation into Google’s business practices says he favors taking a broad view of whether Big Tech dominance is harming innovation, product quality and consumer choice.

Makan Delrahim, a 49-year-old assistant U.S. attorney general, has been in the spotlight since The Wall Street Journal reported May 31 that his antitrust division was planning an expansive probe of Alphabet Inc.’s Google. It is an investigation that could shape the search giant’s future...