Total daily call duration

There is no direct method to check total daily call minutes used at one glance.

What you will have to do is check the time duration of each call during that day and then sum it all up. To do this, you can open the Phone app ➡️ Recents tab: Here, you can choose a call entry and then tap on i for information and see the duration of the call. Do this on all of the day's calls and add up the minutes.

I know that this is not the best way to get what you are looking for. Furthermore, You can suggest this feature directly to Apple by leaving a product feedback here 👉 Product Feedback - Apple 

Axel F.