WifI Scanner

I concur with Bob that Wi-Fi scanning from an iPhone leaves a lot to be desired; however, there is a "built-in" scanner as part of the AirPort Utility app.

To enable it, tap on Settings > AirPort Utility. Slide the "Wi-Fi Scanner" option to the right.

To use it:

1. Tap on the AirPort Utility app.
2. Tap on the "Wi-Fi Scan" option in the upper right-hand corner of the app.
3. For "Scan duration," select the option of choice or leave it set to "Continuous."
4. Tap on "Scan."
5. When done scanning, tap on "Stop." Then tap on "Done."
6. Since scanning uses the battery, disable this feature from the same location you enabled it before.

s there a WiFi Scanner on an iPhone 8+, iOS 15.5

No. iPhone is about the last choice device you would want to use to evaluate Wi-Fi signal quality. Tiny antenna buried inside the iPhone for starters.

If you have a Mac, post back for a few ideas.