in devops sending out email notifications for work items seems limited with the one's listed below:
I want to send an email or a notification in teams when a work item has its due date in 5 days. I also check power automate but couldn't find a template for this. Any ideas?

You can create a Email notification in Azure DevOps when a new work item is created for an issue or a task by following the below steps :
login to https://dev.azure.com/
Select the project on which you want to enable the email notifications --> Go to project settings
Under project settings, click on notifications --> click on Add new subscription as shown in the below image (this will allow you to create a new rule to configure the alert mechanism)
You can refer the attached GIF for reference