Moving subtasks to a different section based on due date

I want to move my tasks and subtasks to my today’s priorities section when the due date is approaching and it says subtasks are not able to do that.

Welcome to the forum, @Jenna_Nicoloff! Are you talking specifically about your My Tasks? If so, subtasks assigned to you show up in My Tasks as “tasks”, so rules you create there for tasks will also work on subtasks (since they look like tasks in My Tasks).