Basic theme.json

				{
    "$schema": "https://schemas.wp.org/trunk/theme.json",
    "version": 3,
    "settings": {
        "appearanceTools": true,
        "color": {
            "custom": true,
            "customGradient": true,
            "link": true,
            "palette": [
                {
                    "name": "background",
                    "slug": "background",
                    "color": "#000"
                },
                {
                    "name": "foreground",
                    "slug": "foreground",
                    "color": "#f9f9f9"
                }
            ],
            "duotone": [
                {
                    "name": "Black",
                    "slug": "black",
                    "colors": [
                        "#000",
                        "#000"
                    ]
                }
            ]
        },
        "typography": {
            "customFontSize": true,
            "defaultFontSizes": false,
            "customLineHeight": true,
            "dropCaps": true,
            "fontSizes": [
                {
                    "name": "small",
                    "slug": "small",
                    "size": "clamp(14px, 1.6vw, 16px)"
                }
            ],
            "fontFamilies": [
                {
                    "name": "Text",
                    "slug": "text",
                    "fontFamily": "Helvetica"
                }
            ]
        },
        "spacing": {
            "defaultSpacingSizes": false,
            "padding": true,
            "margin": true,
            "units": [
                "px",
                "em",
                "rem",
                "vh",
                "vw"
            ],
            "spacingSizes": [
                {
                    "size-name": null,
                    "size-slug": null,
                    "size-size": null
                }
            ]
        },
        "layout": {
            "contentSize": "840px",
            "wideSize": "1100px"
        }
    }
}