Hi Bluestock,
Thank you for using the Apple Support Communities! I understand that you are unable to update your iOS from your device settings. I can help.
When updating your iPhone software through your device settings, you want to be sure you are connected to a reliable Wi-Fi network.
If you are unable to get the iOS update downloaded and installed, please take a look at this article for help: Get help with over-the-air iOS updates - Apple Support. Be sure to follow each step listed in this article, including testing the download on a different Wi-Fi network.
If the same issue remains after all steps above are completed, I suggest using iTunes to update your iOS next. You'll find the steps to do this under the section titled, 'Update your device using iTunes' here: Update your iPhone, iPad, or iPod touch - Apple Support.
If you run into any issues, just reach back out with more details.
Take care!