I don’t know of any that show immediate usage, but that doesn’t mean there aren’t any.
You may also want to check that your phone isn’t letting Apps send data home all the time. Google’s Auto Backup being one of the many Apps that “phone home” a bit.
For Android see the following link for hints https://support.google.com/fi/answer/9458407?hl=en
On an iPhone it will be found in settings > Mobile
Turn off any that are “allowed to use mobile data” option on ones you don’t want using data.
Or you can turn off Mobile data until you want to use it and turn it off again when finished.
Set data syncing times for Emails, Calendar etc to every few hours instead of what is generally minutes or set them to sync only when the phone is connected to Wifi.
Another article that may also help:
