According to [this Washington Post story](https://www.washingtonpost.com/politics/courts_law/supreme-court-trump-tax-returns/2021/02/22/05053b14-751c-11eb-8115-9ad5e9c02117_story.html):

> Vance is seeking the records from Trump’s longtime accounting firm, Mazars.

Thus Trump himself will not be able to refuse to provide the tax return information. Should the accounting firm refuse, it could be held to be in contempt of court, and fined. It is even possible that a responsible person from the firm would be jailed until the firm complies.

I do not see what additional appeals or legal recourse there might be against turning over the returns. But I cannot say that none could be available. There might be arguments that lawyers for Trump or the accounting firm could still raise.

News stories published on 23 Feb 2021 say that Mazars intends to comply with the subpoena. The *New York Times* story ["Supreme Court Denies Trump’s Final Bid to Block Release of Tax Returns"](https://www.nytimes.com/2021/02/22/us/politics/supreme-court-trump-taxes-financial-records.html) said:

> The firm has said it will comply with the final ruling of the courts, meaning that the grand jury should receive the documents in short order. On Monday, Mazars issued a statement saying it “remains committed to fulfilling all of our professional and legal obligations.”