Wired ear plugs for iphones 16 with poor volume control.

I purchased the iPhone 16 Pro in April this year,

I had been using wired ear plugs with the USB adapter which was fine until (as usual) one side of the plugs stopped working. Purchased two wired ear plugs without the need for the adapter. The first unit has no graduated volume control from zero to a scale which is too loud for the purpose for which I use them, namely a mild volume to go to sleep with. It is either too soft to hear, or too loud. The second unit to be used as a spare has exactly the same problem. I then (four days ago) purchased another pair of ear plugs to plug into the USB-C adapter, and that is either full volume or no sound at all.

I want to use the new ear USB-C plugs, so looking for a solution to give a smooth volume incases it should and as expected.