This will NOT work 100% in Office 365 since the timer service that triggers the workflow only runs once per week. If you're ok with a bit of a delay in some cases (for O365) or you're on-prem and have access to change timer job settings, read on.
What you're looking for is under:
List Settings > Information Management Policy Settings > (Select Content Type, e.g. Document) > (check) Enable Retention > Add a retention stage...
At this point, you'll need to get creative if you can't use SharePoint Designer, since setting it to run a custom workflow that sends an email is the simplest option. I've never done it but you should be able to "Transfer to another Location" and have an alert setup in that location whenever something is added? Again, I haven't tried that approach.
As I mentioned, something that's required to make this work is to ensure the timer service that triggers these retention policies runs daily. The two timer jobs you're looking for are "Information Management Policy" and "Expiration Policy". By default they each run once per week. This isn't something you can change in Office 365, however.