Sounds like you are unsure of how you chose to pay your tax due---you say "if I did accidentally choose to mail the check...."
Look at the electronic filing instructions that print out with your tax return, What does it say about how you will pay?
https://ttlc.intuit.com/community/tax-payments/help/how-do-i-review-the-method-i-chose-to-pay-my-fed...
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