The Reminders app on the iPhone is an OS provided App to set reminders. It might not have the fanciest of designs or features But it still works. There are multiple options added to the recent releases.
The app also allows you to set recurring reminders as well.
How to do Recurring reminders on the iPhone?
Tap on New Reminder at the bottom.
Type in the name of the reminder. And then click on the clock icon at the bottom left corner of the screen.
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In the pop up that appears, scroll down and look for Repeat.
In the next section, you can either choose from the listed options or make a custom one.
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In the Custom section, you can choose both the type and frequency.
After you have made the choice, the Reminder will have the custom setting underneath on the main screen.