I've found numerous references on the internet that Red Squadron were an actual unit in the battle of Starkiller base (plenty of references can be found here, with further citation and references). So I know at least they canonically exist and participated. However. Are their fighters (as in the red markings) ever shown on screen (either in battle or on the ground) or do you just see Blue Squadron?
(Alternatively are they just denoted with the same blue markings? (both in and out of universe explanations appreciated if this is the case!))