palette.json

{
    "$schema": "https://schemas.wp.org/trunk/theme.json",
    "version": 3,
    "settings": {
        "color": {
            "palette": [
                {
                    "name": "White",
                    "slug": "white",
                    "color": "#ffffff"
                },
                {
                    "name": "Black",
                    "slug": "black",
                    "color": "#000000"
                },
                {
                    "name": "Yellow",
                    "slug": "yellow",
                    "color": "#f7d600"
                },
                {
                    "name": "Gray",
                    "slug": "gray",
                    "color": "#f9f9f9"
                }
            ]
        }
    }
}