President Joe Biden will advocate plans to increase taxes on the wealthy and corporations as well as to lower prescription drug prices in his State of the Union address on Thursday night, in what aides describe as an effort to lay out second-term proposals for protecting and implementing his economic agenda. Mr. Biden’s vow to raise taxes on the rich faces formidable obstacles in Congress. Republicans, who abhor any tax increase, narrowly control the House and Democrats have a slender hold over the Senate. The White House didn’t offer additional details, but on the campaign trail recently, Mr. Biden has been advancing the idea of raising the corporate tax rate from 21% to 28% as well as a tax hitting capital gains for billionaires.