If you need an extension to file a Form 1041 for your brother's estate, then you need to file Form 7004 which is not included in the personal versions of TurboTax.
Form 7004 is included in the Business edition of TurboTax which supports the preparation and filing of Form 1041.
You can download and prepare Form 7004 from the IRS web site at the link below.
https://www.irs.gov/pub/irs-pdf/f7004.pdf