@vinceASPECT: There are a couple obstacles you're faced with...
1. Your provider may sell tethering as a service and if so, most of them go out of their way to make it difficult to bypass paying for this service when you want to share your 3G/4G/5G connection with a blue-tooth or wifi connected device.
2. Your device/phone/tablet, especially those whom are branded (when it boots it shows the service provider's logo/splash screen/etc.) may be programmed to avoid third party tethering.
All of a sudden, after a system update, my app used for usb/wifi/bt tethering stopped working...
This is what I usually hear.
Back in the day there was an app called Fox-Fi which was as close as I could find to do just what you're after -- without having to root the phone. Whether it still exists and/or operates on newer Android releases is unknown to me. $oogle on the other hand has been in the pockets of the service providers and they tend to clean out apps that cross certain lines... so if you find something that works well today... and it becomes popular... praise it while it lasts - but
expect it not to.
Good luck!