I have a slightly different spin on this question - I never asked for any reminders, but recently "New Outlook" has started suggesting emails that I might want to reply to from several days ago. There is an option to dismiss the reminder, and a question "Is this message reminder useful?". I'm assuming there is some kind of AI deciding which types of emails I might want to respond to, but I'd really like to know more about the decision process. How does New Outlook decide which message I might have wanted to reply to?
I suspect this AI version might be replacing the task you were trying to find. I couldn't find anywhere in settings to enable/disable or adjust the suggestions. If you see these, make sure you answer truthfully about whether or not the reminder was useful - it may impact your future suggestions. AI is here!
Editing to add - the suggestions just appear at the top of my Inbox, even though I have it sorted by Received. Suggestions clearly override my sort decision whether I want it or not.