You will not be able to "fix" this in the return and the IRS will not assess penalties for late filing or payment as long as you meet the extended due date.
That extension was granted after TurboTax released its 2020 tax software, and it is automatic for anyone living in Texas. This means you won't have to file forms requesting more time to file.
If, however, you decide to file before June and don't want to pay any tax due until June 15. you'd have to select the "mail-in payment option" and "4/15/2021" as the payment date; the program won't be updated to show that Texas filers have an extra 2 months to pay.
See Extension and Tax Relief for Texas Winter Storm Victims for additional information.
