What version are you on now? There was an update about that size about a week ago. Details from the AT&T page:
Here is the current update: Android 8.1.0 Oreo
The details
Release date: August 24, 2018
Android version: 8.1.0
Security patch level (SPL): August 1, 2018
Baseband version: N960USQU1ARH4
Build number: M1AJQ.N960USQU1ARH4
File size: 212.5MB
The updates
What's new: User Experience (UX) and stability enhancements
What's changing: Android device security updates