With the online version of Turbo Tax how can you download a complete set of filing documents, as opposed to just the three page 1040 form offered thru the dashboard?

Depends on which tax year you are referring to ... the 2022 or a prior year ?

Prior years :

To access your prior year online tax returns sign onto the TurboTax website with the User ID you used to create the account - https://myturbotax.intuit.com/

Start the 2022 online tax return (if you have not yet done so)  by entering some personal information (about a dozen screens) even if you will NOT use the TT program for the 2022 return.  Then click on Tax Home on the left side of the screen.

On the Tax Home webpage -

Scroll down to the section Your tax returns & documents.  Click on the Year and Click on Download/print return (PDF)

If you used the desktop CD/Download editions installed on your computer, the only copy of your tax data file and any PDF's will be on the computer where the return was created.  TurboTax does not store online any returns completed using the desktop editions.

2022: 

Please follow the instructions below to preview your tax return before filing.

How do I preview my TurboTax Online return before ...

Please follow the instructions below for a copy of your tax return after filing.

How do I get a copy of a return I filed this year ...

If you have filed your federal tax return and it has been accepted by the IRS -

To access your current or prior year online tax returns sign onto the TurboTax website with the User ID you used to create the account - https://myturbotax.intuit.com/

When you sign onto your online account and land on the Tax Home web page, scroll down and click on Add a state. 

This will take you back to the 2022 online tax return.

Click on Tax Tools on the left side of the online program screen.  Then click on Print Center.  Then click on Print, save or preview this year's return.  

Choose the option Include government and TurboTax worksheets