Is the soffit area open?(where the blue arrow is pointing)Here is an artical with pictures of my coop.
https://www.backyardchickens.com/articles/my-amish-made-chicken-coop.75799/
How about both the gable ends(red arrows)?
That would be the best place to add vents.
Looks like tight space for the big feeder and water.
How many birds?