The recent SCOTUS ruling on the ability of the Manhattan DA's office to enforce their subpoena applies to the accounting firm Mazars (who has copies of the tax returns and acts as Trump's agent in dealing with the IRS) and not Trump himself.
"...Vance is seeking the records from Trump’s longtime accounting
firm, Mazars." Supreme Court rejects Trump's final bid to shield tax returns from Manhattan prosecutor - The Washington Post
If Mazars does not comply, it and individuals (staff or board or corporate members) can be held in contempt and jailed and/or fined.
There's little reason for Mazars to fight the subpoena; their reputation and livelihood would be at risk if they violated the law and ignored the subpoena. Trump is simply a Mazars client, and they act as his agent.
Vance... had subpoenaed the records from the Mazars accounting firm...
Mazars has said it would comply with the subpoena, but Trump (had)
sued to block the records’ release. Supreme Court won’t halt turnover of Trump’s tax records - The Washington Post
And, it's important to note that
"The court’s action does not mean Trump’s tax records are to become
public. Vance has said they would be protected by grand jury secrecy
Court ends Trump's bid to shield his tax returns, efforts to challenge
election losses - The Washington Post
Update: and note that probably due to that ruling, on March 2nd,
A U.S. House of Representatives panel reissued a subpoena seeking
Donald Trump’s tax and financial records, saying in a memo made
public... it needs the documents to address “conflicts of interest” by
future presidents. U.S. House panel reissues subpoena for Trump's tax records | Reuters