@Kmic No your tax return will not be 'flagged" if you mail a paper tax return. Millions of tax returns are mailed to the IRS each year.
See this TurboTax support FAQ for printing a tax return for mailing - https://ttlc.intuit.com/community/printing/help/how-do-i-print-and-mail-my-return-in-turbotax-online...
Since your tax return included a deceased person the IRS usually rejects these returns for e-filing.
See this IRS website - https://www.irs.gov/e-file-providers/list-of-available-free-file-fillable-forms
Decedent Returns- The program might not efile a decedent return. If the Primary or Secondary taxpayer on the return is a decedent, it may be necessary to mail in the return.
