How do I see tasks due today, past due, etc?

The Filter View has built in “filters” that allow you to see Tasks due today, overdue Tasks, and upcoming Tasks. On iOS, the Filter View is the 3rd tab at the bottom of the app.  On the desktop, the Filter View can be toggled on and off using the icon with three vertical bars on the titlebar area.

To learn more, check out What’s the Filter View?