An online TurboTax account does not store your return that you prepared using the CD/download, nor does the online account "know" that you used the CD/download last year. The return you prepared using the CD/download is only stored on your own hard drive. It will not "show up" in your online account.
You can transfer the tax file to the online version if you want to though. Even if the 2020 tax file is on your hard drive you can transfer it to the online software at the very beginning before you enter any other 2021 data
https://ttlc.intuit.com/questions/1900883-how-do-i-transfer-last-year-s-return-to-turbotax-online
When you use the downloaded program none of that information is stored in the ONLINE system ... it is only on the computer you used or any backups you made.
Now when you start the 2021 return you are asked what you used last year and if you say the downloaded version then you will be directed on how to transfer that info into the online system.
An online TurboTax account does not store your return that you prepared using the CD/download, nor does the online account "know" that you used the CD/download last year. The return you prepared using the CD/download is only stored on your own hard drive. It will not "show up" in your online account.
You can transfer the tax file to the online version if you want to though. Even if the 2020 tax file is on your hard drive you can transfer it to the online software at the very beginning before you enter any other 2021 data
https://ttlc.intuit.com/questions/1900883-how-do-i-transfer-last-year-s-return-to-turbotax-online