Bluetooth and notifications

Every article I have read says that when the iPhone is connected to a Bluetooth device that your text notifications etc. will only come through the paired Bluetooth.

My issue is this ; I do not have a vehicle with Bluetooth in it but I drive for a living. I have a Bluetooth headset which goes in one ear only with the microphone that I use for all my calls .

I do not have this in my ear constantly as it rests on the dash on the charger when I am not using it. I have only had this phone for three days and I have noticed that when I am at work and it is paired with my Bluetooth headset I do not receive any notification sounds from the phone speaker itself, However the phone calls still come through on the phone speaker.

I have a brand new iPhone xs and This is my very first iPhone I have been an android user for years.

Is there anyway possible to get my notifications to come through the phone speaker and not my Bluetooth headset as I don't hear them when I am not wearing the ear piece.

I am happy to try out any third-party apps which will make this work for me.

Thanks in advance