@polandluigi Yes, it is possible, you can change the videomode in the recalbox.conf file, or you can go further and change it in the recalbox-user-config.txt file (you will find several topics talking about the config.txt file, but the file recalbox-user-config.txt keeps your changes after an upgrade, config.txt does not).
See this:
https://recalbox.gitbook.io/documentation/tutorials/video/display-configuration/complete-guide-on-video-configuration