Here are some handy links found
https://www.raspberrypi.org/forums/viewtopic.php?t=25933 https://raspberrypi.stackexchange.com/questions/46153/detect-hdmi-and-start-gui/46158#46158 (the guide from the Raspberry Pi site) https://www.raspberrypi.org/documentation/configuration/config-txt/video.mdYou can start playing with the command and see if you can switch manually between resolutions, on the fly. If this works, then you can incorporate it in a script to be run at boot.