Yes, you are right. It can’t be changed.
Printer settings is a global setting, once we use default Portrait mode in page orientation, it applied to all printers, despite we switch to another printer, default orientation is still Portrait, need to change manually.
In other words, if we change the mode through printer settings, the printer will use the mode you choose as the default mode, once we change the printer to landscape mode all programs will print in landscape mode instead of portrait.