Welcome to the Bunnings Workshop community @lenacurly. It's wonderful to have you join us and many thanks for your question.
I trust some images of these red archways would assist our members in providing some great solutions.
Obviously, painting the arches would be an option and whitewashing would knock the colour down considerably. I'm not sure if a whitewash would disguise the red colour completely as washes are generally semi-translucent. Red is a bold colour to cover at the best of times.
We look forward to hearing more about your project and possibly seeing some images of the archways.
The mortar in between is also dark. I don't want to paint them white...I was wondering whether whitewashing would be good, or perhaps lime.
I tested white on them but it almost seems to need a hint of another colour, maybe grey. They are smooth.
The wood is being painted white and a lovely turquoise on the bits of wall that are in the room. I think the beams might look good white. But that still leaves the bricks.
Sorry I posted earlier but didn't know how to edit to put in pictures.