I amended my 2020 return using TurboTax online and submitted it using e-file. I owe more tax. I can’t tell if my e-file is going to deduct my bank account, or mail check?

Whichever method you checked when you e-filed is how your payment will be applied.  If, for some reason, you did not have the opportunity to make a selection, don't worry you will receive a bill from the IRS.  Here are some steps that will help you.

You can use the steps here below to help you find your tax payment date and banking information or how you chose to pay, on your return. 

• Log into your account and click on My TurboTax (or Taxes) at the top 
• If the drop down appears, choose My Tax Timeline (if it doesn’t appear when you click, it may have taken you directly to the page once you clicked My TurboTax.
• Scroll down to section Some Things You Can Do 
• Click on Download all forms and worksheets
• On the return, Part V of the Federal Information Worksheet will have your auto debit date and bank account info
• And Part VI on the State Information Worksheet will have your state auto debit date and bank account info for that payment

And if you chose to have them withdraw from your bank account, generally, the funds are withdrawn on the payment date you specified if your return has been accepted. If you still don't see the debit 7-10 days after your return has been accepted and your specified date, you will need to call the IRS e-file Payment Services at 1-888-353-4537, if this is a federal tax payment you owe. If you didn't specify a date, then April 18th is the default payment date.

Or contact your state tax agency, if you owe a state payment. You can go here https://ttlc.intuit.com/questions/1901670 and choose your state and it will take you to their contact page with phone numbers to reach them. 

https://ttlc.intuit.com/replies/3299924

Per @AndreaC1