Hi Nu_Flow,
I think your purpose is to send a notification to the last user of all the documents which have elapsed the X time.
I have made a flow for your scenario, please check it for a reference.
I assume that if the file has not been modified for 3 days, it will send a notification.
You can change the X time as you want.
The expression of filter array is:
@less(addDays(item()?['Modified'],3,'yyyy-MM-dd'),formatDateTime(utcNow(),'yyyy-MM-dd'))

Best regards,
Zhonys