sp-dev-fx-webparts/samples/react-securitygrid/config/serve.json

{
    "$schema": "https://developer.microsoft.com/json-schemas/core-build/serve.schema.json",
    "port": 4321,
    "initialPage": "https://localhost:5432/workbench",
    "https": true,
    "api": {
        "port": 5432,
        "entryPath": "node_modules/@microsoft/sp-webpart-workbench/lib/api/"
    },
    "serveConfigurations": {
        "default": {
            "pageUrl": "https://russellwgove.sharepoint.com/sites/testazad/_layouts/15/workbench.aspx"
        }
    }
}