@Ericthegeat No, that's not working for the Pi5 and - with current RaspiOS - other models anymore. Everything you find that says modify config.txt and add/change ... will not work as far as video resolution is concerned.
Those configuration options were read by the RPI firmware and applied directly through VPU commands, but the Pi5 doesn't have a firmware and the other models are also not using that approach anymore, resorting to 'standard' Linux methods for (auto/self) configuration during boot and after the boot has completed.
EDIT: Out of curiosity, how is this kind of converter configured on a normal PC with Linux ? What are the commands/configurations needed if you'd have a Linux PC and want to use it ?