See this TurboTax support FAQ for changing from mail to e-file - https://ttlc.intuit.com/community/e-file/help/how-do-i-change-from-mail-to-e-file-in-turbotax-online...
You can use the IRS payment website to make any amount of payment you want to for the federal taxes owed. As long as the total of the taxes owed is paid on or before April 15, 2021 - https://www.irs.gov/payments
If you do go that route, then when asked for how you want to pay the federal taxes owed choose the pay with check option and then e-file your tax return. You would not send a check if you are paying on the IRS website.
