Apple is taking a page from productivity apps like Things 3 to make its Reminders app easier to use and more robust.
In iOS 13, you'll be able to jot down reminders like you currently can, but you'll be able to add dates, times, locations, photos, check lists, and flags to really get specific about your lists and to-dos.
Siri will also be able to suggest new reminders based on what you're doing. So if someone messages you to make plans, Siri can automatically create a reminder for you.