A little color contrast is fine. Problem is tying in color with something else in vicinity e.g. window trim or window shutters. Would look odd if absolutely everything were white and railings/posts were different. .

Somewhat concerned about cedar. Had a deck & railings from Cedar when house purchased. Posts were so rotted that I could push bare thumb through posts. Eventually, a board gave when I stepped on it and I concluded I needed to redo the whole deck.. Cedar heartwood is rot resistant, but nearly impossible to get true heartwood( need old growth timber). Most cedar sold is neither insect nor mold resistant. You would have to stain it to protect it. In addition, cedar is relatively soft. If you want wood, it would be cheaper and longer lasting to use pressure treated wood and a cedar color staim--still needs restaining every now and then.
Vinyl railngs are also a possibility. Not sure about degree of resistance to mildew.
Aluminum railings would be extremely low maintenance and easier to install, but not achieve your wood tone.