send a Slack DM to the assignee 3 days before the issue's enddate.

[정대규]

I would like to send a Slack DM to the assignee 3 days before the issue's enddate.

The username for jira and the username for slack are the same.
Is there a way to send a message only to the assignee via DM, not the channel?

And I want to know JQL to search within 3 days of enddate in automation
(Ex: due >= 3d AND due <= 0d)