I need to amend my 2019 because the taxpayer died prior to submitting tax return and I did not show that.

If you are filing the amended return, you can follow the instructions here.

Be sure to mark the box in the personal information you are filing on behalf of a deceased individual. 

When you file the amended return, it will provide you all the instructions with what you need to send in (if anything). 

{Edited 02:02 PST, 02/25/2021}