President Volodymyr Zelensky of Ukraine has signed off on legislation that would significantly expand the government’s regulatory power over the news media, a measure that journalists have warned will erode press freedom.Mr. Zelensky, whose administration has been criticized for undermining press freedoms, ordered the drafting of a law increasing media regulation in 2019.The measure was passed by Ukraine’s Parliament earlier this month along with a spate of other bills that lawmakers say were intended to help the country meet the European Union’s legislative conditions for membership. The bills included measures to protect the rights of national minorities. Mr. Zelensky signed...