iPhone 16.3.1 can not bluetooth pair with MacBook air ventura 13.2.1

See the information in: Bluetooth: Why can't I pair my iPhone or … - Apple Community

If you are attempting to use Handoff/Continuity or AirDrop, that does involve Bluetooth but the devices are NOT paired; Bluetooth just needs to be on and the devices in range of each other. The following may help with Handoff/Continuity issues: Use Continuity to connect your Mac, iPhone, iPad, and Apple Watch - Apple Support

Also see Share files between your Mac and Bluetooth devices - Apple Support