Create a reminder flow

1. Create a SharePoint list with at least one DateTime (you can use Modified date) column in the current view.
2. Select Automate > Set a reminder > Date deactivated (this is the column with the DateTime for the reminder).

   

3. Optionally, you might need to sign into the the services that this Power Automate template uses.
4. Select Continue.
5. Provide a Flow name and the number of days prior to the DateTime column entry when you want to receive the reminder alert on the Set a reminder card.

   

6. On the Set a reminder card, select Create .
7. You’ll receive the following message, indicating that the flow was created:

   

Reference 

https://docs.microsoft.com/en-us/power-automate/create-sharepoint-reminder-flows