Karabiner-Elements Complex Modification to Increment/Decrement Volume with higher precision on mac. You may need to change f11 to your volume up key and f12 to volume down key. You may also need to change the modifers to "left_shift" and "left_option". The reason for the weird mapping is because of my mechanical keyboard

PrecisionVolumeControl.json

{
  "title": "Volume Precision Control",
  "rules": [
    {
      "description": "Precise Volume Increment",
      "manipulators": [
        {
          "type": "basic",
          "from": {
            "key_code": "f11",
            "modifiers": {
              "optional": ["any"]
            }
          },
          "to": [
            {
              "key_code": "f11",
              "modifiers": ["left_alt", "left_shift"]
            }
          ]
        }
      ]
    },
    {
      "description": "Precise Volume Decrement",
      "manipulators": [
        {
          "type": "basic",
          "from": {
            "key_code": "f10",
            "modifiers": {
              "optional": ["any"]
            }
          },
          "to": [
            {
              "key_code": "f10",
              "modifiers": ["left_alt", "left_shift"]
            }
          ]
        }
      ]
    }
  ]
}