How high are you placing the rod?

How high are the ceilings?

Find something in your house of similar size and have someone hold it up where you plan to place it. This should give you a good visual of what size will work best.

First? Why a rod and curtains over FRENCH doors at all? French doors need to swing. Is this a 6' set of exterior, or are they interior to an adjacent space? If it is an issue of covering glass, there are far better ways. Take a picture of exactly what you are doing? because a "traverse" rod suggests you want to be able to cover the doors fully.

Why traverse if modern is the look you want ? I need a lot more info . Which way do the doors open ? Any rod can be thta width and not be wood but we need more info Pics of the space is agood place to start. posted here in a comment DO NOT start another post

The ceilings are 9’. There are two sets of French doors and although they are technically exterior doors the builder put them in wrong so only one door of each set opens and the wrong way! We want to add curtains (which we used to have) for insulation from the cold air that comes in. We occasionally have to open one door so the traverse rod allows us to push them to one side over the center support. I’m including a picture for reference.

Picture of the French doors on either side of fireplace.