Is there a window rule for ‘close’ to be applied when an application starts, instead of ‘Minimized’?

Why would anyone want to close an application at launch? Well, the appimage for Viber doesn’t let you set Minimize to Tray at start-up. So, for now I use a window rule to minimize the window at least. ‘Close’ would send it to the tray, but I can’t find such a rule.