Short on time so quick reply. Your question was name a US president who made a unilateral decision or took an act that affected the economy. I identified the president and described the measure. The Trump-initiated trade war with China negatively impacted the US economy and is widely viewed as a failure, and that was the assessment while Trump was still president. What Biden did or didn't do after the fact doesn't change that.Yet Biden has continued them. That may be a worse decision- to continue a policy he knows is detrimental to the economy.
These tariffs were much easier to impose than to lift. There's been pressure from labor unions and a number of American companies to keep the tariffs in place. At the same time, lifting the tariffs would be perceived as being "weak on China." Also, the tariffs could be used as a bargaining chip for a significant "get" at the appropriate time. Finally, the US economy is currently booming and is the envy of the world. There are 5 million more US jobs now than prior to the pandemic. Wage growth is outpacing inflation. There's no compelling reason to lift the tariffs now.