%{issue.dueDate}
When cast to text, the output depends on the jira.date.time.picker.java.format parameter set in your Jira instance.
jira.date.time.picker.java.format
19/Mar/20 would be returned for dd/MMM/yy h:mm a
dd/MMM/yy h:mm a
Valid numerical input
2020-01-31 14:35
The allowed date-time format is defined at jira.date.time.picker.java.format
Additionally you can use the formats allowed in JQL queries:
00012
%{parent.dueDate}
00039