When the person died in 2011, they were “deemed” to have “disposed” of the property at that time. So, they would have to report any capital gain or loss on their 2011 return, unless it was their principal residence. At that time, you didn’t need to report the sale/disposition of a principal residence if the property was your principal residence for every year you owned it.
If the property that was sold in 2021 was owned by the estate of the deceased, then the sale would not be reported on a T1 personal tax return. Instead, you would need to file a T3 Trust Income Tax and Information Return.
TurboTax can’t be used to prepare a T3 return, but Intuit has another program called Profile OnePay that can be used. Profile uses EFILE, not NETFILE to submit returns, so you don’t have an EFILE account, you will need to print and mail your return. It is also for Windows only. You can learn more about Profile OnePay on their website here: Profile Onepay - Single return tax preparation software
This TurboTax FAQ has more information regarding preparing returns for the deceased: Can I prepare a return with TurboTax for someone who has died?