I filed multiple tax returns for 2019

Sorry--you messed up big time.  The online software is only for 2019--no other year.  Each tax year has to be filed separately using the forms for the specific tax year.

Was the return accepted or rejected?  

https://turbotax.intuit.com/tax-tools/efile-status-lookup/

If it really was accepted, you have to wait for it to be fully processed and then prepare an amended return.  Do not try to do anything yet.  When the IRS starts processing it, you may find yourself under review.

Here is what you were supposed to do     AND each one should have been a separate return:

To file a return for a prior tax year

If you need to prepare a return for 2016, 2017, or 2018 you can purchase and download desktop software to do it, then print, sign,  and mail the return(s)

https://turbotax.intuit.com/personal-taxes/past-years-products/

Remember to prepare your state return as well—if you live in a state that has a state income tax.

When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s.  Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS/state received the return.

Note:  The desktop software you need to prepare the prior year return must be installed/downloaded to a full PC or Mac.  It cannot be used on a mobile device.

If you are getting a refund, there is not a penalty for filing past the deadline.  If you owe taxes, the interest/penalties will be calculated by the IRS based on how much you owe and when they receive your return and payment. The IRS will bill you for this; it will not be calculated by TurboTax.

https://ttlc.intuit.com/questions/1900990-how-do-i-file-a-prior-year-tax-return