If there is, you can tell me
Use the Tor browser. Your regular browser is not configured to keep you anonymous.
You will not be able to start Tor or a VPN from your browser.
To use Tor directly, you need to download the Tor application itself and configure it as a service so it runs whenever you start your computer. For a VPN, this depends on your operating system. If you configure your VPN in Windows, you can start it using the rasdial command line utility.
For non Tor Browser, no. GM script doesn’t have any access to web browser’s proxy setting.