am having error setting cname.vercel-dns.com as destination address

i want my /app to redirect to app.bilwills.tech but also let my bilwills.tech still works

import type { NextConfig } from "next";

const nextConfig: NextConfig = { /* config options here / images: { remotePatterns: [ { protocol: "https", hostname: "", }, ], },

basePath: "/app", };

export default nextConfig;