Hi RC21Ca,
Welcome to the Apple Community.
Apple support's article: "Find your keys, wallet, and more with AirTag"
Says: "Use Precision Finding to pinpoint the location of your item
If you have a supported iPhone model with Ultra Wideband and your AirTag is nearby1, you can use Precision Finding to help find it, even if it's stuck between couch cushions or hiding under a stack of mail".Â
"If your AirTag is out of range of your connected device, get directions to it first."
"Â AirTag uses the Find My network, an encrypted, anonymous network of hundreds of millions Apple devices that can help you find your things."Â
Also: "Environmental factors, including wall materials or objects between your iPhone and your AirTag, might impact performance."
And
"If your iPhone or region doesn't support Ultra Wideband, or your AirTag is outside of the range of your device, you can get directions to its location."
Complete article: https://support.apple.com/en-us/HT210967.Â
All the best :-)