Yes, it is possible to download an older version of Opera with the former GUI. You can find it on the Opera website's downloads page. Once you have downloaded the installer, you can run it to install the older version of Opera. However, please note that Opera will automatically update itself to the latest version unless you disable automatic updates. To disable automatic updates, you can open Opera and go to Opera > Settings > Advanced > Update. Uncheck the box next to Automatically check for updates and click OK.