Line 19 appears on the hard copy version of form T3 on the CRA website, so why does it not appear on the T3?
The CRA guide is referring to Line 19 of a T3 return (not a T3 slip).
T3 returns (Trust Income Tax and Information Return) are different than the final return. T3 returns cannot be prepared with TurboTax as they are Estate returns, not personal tax returns. Here's a link for more details: https://www.canada.ca/en/revenue-agency/services/tax/individuals/life-events/what-when-someone-died/...