nginx change timeout response

We have a reverse proxy server with nginx. We want to pass a static page in case the reverse proxy timesout.

Current configuration is:

server {

    listen 443;
        ssl on;
        ssl_certificate /etc/ssl/****.crt;
        ssl_certificate_key /etc/ssl/****.key;
        ssl_protocols TLSv1.2 TLSv1.3;

        server_name ****;

        access_log            /var/log/nginx/****.log;
        error_log             /var/log/nginx/****.log;
        location / {

                proxy_set_header        Host $host;
                proxy_set_header        X-Real-IP $remote_addr;
                proxy_set_header        X-Forwarded-For $proxy_add_x_forwarded_for;
                proxy_set_header        X-Forwarded-Proto $scheme;

                proxy_read_timeout  30;

                proxy_ssl_name $host;
                proxy_ssl_server_name on;
                proxy_pass https://****;
        }

        location /Callback/reservebalance {
                proxy_pass https://****;
                proxy_read_timeout 2;
                proxy_connect_timeout 2;
                proxy_send_timeout 2;
                return this response if server times out on proxy{
                    default_type application/json;
                    return 200 '{"response":"my static response"}\n';
                }
        }
}