Sorry you can't get it back. It like dropping it in the mailbox.
You now have a problem. You have to wait and see if your efile gets accepted. If they reject it for something you can change it around to be for 2019
But if they accept it you need to wait some more for it to fully process and you get the first refund. Then you need to Mail in an Amended 1040X return to change it to be for 2019.
You can check your efile status here https://turbotax.intuit.com/tax-tools/efile-status-lookup/
How to amend an Online return
https://ttlc.intuit.com/community/amending/help/how-do-i-amend-my-turbotax-online-return/00/
Amended returns can only be MAILED not efiled.