iPhone Bluetooth

There may be something in the following that will help: If Personal Hotspot is not working on your iPhone or iPad (Wi-Fi + Cellular) - Apple Support

Be sure to check all of that support article, including the "If you still can't connect to Personal Hotspot with Bluetooth" section and if nothing else works, the "Get more help" section.

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

iPhones don’t typically explicitly pair to other Apple devices using Bluetooth (except AirPods).

You told us how you’re trying to do something. Instead you should tell us what you’re trying to do. We can offer much more help that way.

FoxFifth provided an excellent response. The one significant piece of your explanation was:

Emmanuelyeb wrote:

I normally connect my iphones to share internet.