When using the online editions, your tax return is automatically saved as a tax data file. There is no need to name the file since it is always available when you sign onto your online account with the same User ID you used to create the online account.
If you ever need to download the tax data file from the online account it will download with a file extension of ,taxyyyy, where yyyy is the tax year of the file, eg .tax2025 for tax year 2025.
See this TurboTax support FAQ for downloading a tax data from an online account - https://ttlc.intuit.com/turbotax-support/en-us/help-article/import-export-data-files/save-turbotax-o...