President Biden and his aides came into office with deep experience in trans-Atlantic affairs. But over four years, they focused too on the Pacific, where China strains to be the dominant player. Their main effort: building up alliances to counter China.

President-elect Donald J. Trump has already signaled a different approach to China. He invited Xi Jinping, China’s leader, to his inauguration on Monday. The two spoke by phone on Friday, and Mr. Xi is sending China’s vice president, Han Zheng, to the ceremony, a break from China’s tradition of having its ambassador in Washington attend.

The Biden administration’s final activities aimed at China stand in contrast to that. Mr. Biden held a call last Sunday with the leaders of Japan and the Philippines to firm up a new three-way security arrangement he helped build. Secretary of State Antony J. Blinken visited South Korea and Japan this month on his final official trip.

In the telling of Mr. Biden and his aides, they are handing Mr. Trump a sharpened competitive edge on China, the greatest rival to the United States.

Of all of Mr. Biden’s foreign policies, his approach to China could ultimately be seen by historians as existing in a continuum. His administration built its own structure on a foundation of competition laid by Mr. Trump’s team and is now turning it over.

It is unclear what Mr. Trump will do with that. He admires the autocratic Mr. Xi, and sees China mainly through the lens of economic negotiations. Mr. Trump’s billionaire advisers, including Elon Musk, want to maintain and perhaps expand business dealings with China.