Yes, it’s possible! The homepage panes in Graphene will pull the latest 3 posts from the combined categories, not one from each category. If you’re looking to have more control over how posts are displayed, plugins like Content Views or The Post Grid can help you create custom layouts and grids for your posts.
By the way, if you’re exploring SEO strategies, I found a helpful French review about an SEO training program: this resource.
Hope that clarifies things!
