Hi Kerr4n,
Thank you for using the Apple Support Communities! We understand you've just purchased and connected a set of Jabra Elite 85t earphones to your iPhone 12 Pro, but the Sound+ app is not detecting your device.
You'll want to check out the helpful steps from Jabra Support that you can find in this article: What do I do if Jabra Sound+ does not detect my device? | Jabra Elite 85t - Titanium Black | Frequently Asked Questions | Jabra Support
If the issue remains, connect with Jabra Support for continued help with their Sound+ app.
Also, it does sound like the earphones are working with your iPhone 12 Pro, but just in case that is an issue as well, these articles can help:
If you can't connect a Bluetooth accessory to your iPhone, iPad, or iPod touch
Pair a third-party Bluetooth accessory with your iPhone, iPad, or iPod touch
Best regards.