Keychron - remap microphone button with Karabiner

gistfile1.txt

{
    "title": "Remap x to y",
    "rules": [
        {
            "description": "Remap x to y",
            "manipulators": [
                {
                    "from": {
                        "key_code": "spacebar",
                        "modifiers": {
                            "mandatory": [
                                "fn"
                            ]
                        }
                    },
                    "to": [
                        {
                            "key_code": "f12",
                            "modifiers": [
                                "left_command",
                                "shift"
                            ]
                        }
                    ],
                    "type": "basic"
                }
            ]
        }
    ]
}