My iPhone SE bluetooth is not working, it can’t see most devices and when it can see my iPad it won’t pair

You've put the receiver in pairing mode per the directions from the receiver manufacturer? No device will be seen by iPhone Bluetooth the first time UNLESS it is in pairing mode. Once connected, it will connect again and again. But it has to be paired the first time and that requires the device to be in pairing mode.

iPhone and iPad do NOT pair via Bluetooth. iPhone Bluetooth pairs with external devices such as headphones, speakers, keyboards, etc. What are you hoping to accomplish via Bluetooth between your iPhone and iPad?

Also check the manual from the stereo receiver, some are limited to one connection in memory. Also, if your partners phone is connected to the receiver it won't see yours, have them temporarily turn off Bluetooth in Control Center.

Thanks deggie. I should have made mention of the fact that the receiver may only be able to be paired with one device at a time.

That's great!