You cannot change from Married Filing Jointly to Married Filing Separately after the due date of the tax return.
For other changes to filing status on a 2019 tax return you would have to file an amended tax return for tax year 2019.
See this TurboTax support FAQ for amending a 2019 tax return originally completed and filed using TurboTax - https://ttlc.intuit.com/community/amending/help/how-do-i-amend-my-turbotax-online-return/01/27577
