Last October, Facebook began testing a new set of image presentation options for posts, with preset display formats for multi-image uploads, enabling more ways to showcase your visuals.
Since then, the format has been spotted 'in the wild' by various users, and now, it appears to be getting a broader release, with several reports of the option appearing in the composer for multi-image posts.
As you can see in this example, posted by user Mamum Billah (in February), the new options appear at the bottom of the post composer, giving you four different image display formats to choose from. Users in different regions are now reporting access to the option, so it seems that it is on the way to all, sometime soon.
That will provide new considerations for your Facebook posts, which could help to make your updates stand out in feeds. But then again, if everyone is using them, the novelty will wear off pretty quick - what could be more interesting, from a brand perspective, is considering how you can utilize these types of formats to better showcase your products, and boost your promotions with the added angles and display tools.
That is, of course, if it gets released for Pages. At present, it only appears to be available for personal profiles, but it'll likely be expanded to Pages also, which could give you new options to consider.
It's not a massive shift, and there are various existing tools on the market which facilitate multiple image layouts and formats (including Instagram's Layout collage tool). But it could be a simple, quick, and integrated option to add more flair to your updates.
If you're not seeing the new display formats in your composer yet, they'll likely make it to you sometime soon.