Hi @jodnt 
Welcome to the Community!
By default, the user won’t receive a reminder that their task is overdue.
Not to worry though, you can easily add this via an automation.
I’d recommend checking out the ‘Due date’ section of the automation centre to see all of the available automations.
One automation you might like to try is the following:
This will notify the user at a certain time period (for example, every day) until the item is marked as complete.
I hope this helps! Remember to mark as solved if this answers your question 
Best,
Dani