No, your Instagram posts won’t be automatically shared to Facebook. But If you’d like your posts to be published to Facebook, you can schedule them to both profiles at once with Later! See how to schedule a post to multiple social profiles.
Note: Even if your Instagram is set up to automatically push posts to your Facebook, this feature won’t work when Auto Publishing. This is a limitation set by Instagram.
Note: If you’re using notification publishing, you can choose to share your post to a connected Facebook before publishing in the Instagram app.