Automations based around due dates

I am trying to work with activity due dates to trigger events for automation. In my opinion, this would be one of those essential triggers i.e. due date hits and a manager is notified that something did not get completed or due date hits and a series of emails is sent to client and employee speaking on the missed due date.

In our industry, we renew our clients a year later and if we have a die date in 9 months then we can trigger reminder emails for 90 days to then get a renewal for the 12 months later. This seems like a very simple feature that when a certain due date is reached then it will trigger an event. I see that I can make a trigger for when a due date is changed but not when the due date has been reached. Am I missing something?

I look at other posts here on the forums, and I find they are full of people telling to sell me other features or services to get the functions I need. I would kindly ask not to be sold a different option but rather an answer on how I can the platform we currently pay for to automate the things we need to automate. Sorry for the rant.