President-elect Donald J. Trump filed an unusual brief on Friday asking the Supreme Court to block a law that requires TikTok to be sold or shut down by Jan. 19.

The deadline falls a day before Mr. Trump is to be inaugurated, and the brief asks the justices for the delay so that he may address the matter.

“President Trump opposes banning TikTok in the United States at this juncture,” the brief said, “and seeks the ability to resolve the issues at hand through political means once he takes office.”

The brief took no position on the legal question that the justices are set to consider when they hear arguments in the case next month: whether Congress violated the First Amendment by effectively banning TikTok. Adopting a distinctive tone at odds with the sober and measured arguments more typical in Supreme Court advocacy, the brief instead touted Mr. Trump’s expertise.

“President Trump alone possesses the consummate deal-making expertise, the electoral mandate and the political will to negotiate a resolution to save the platform while addressing the national security concerns expressed by the government — concerns which President Trump himself has acknowledged,” the brief said.

Mr. Trump, the brief added, is particularly knowledgeable about social media in general and TikTok in particular.