Can the ShortPixel Image Optimizer plugin for WordPress help with the "Properly size images" issue?
The ShortPixel Image Optimizer plugin only optimizes the images, replacing them with their compressed versions. It does not scale them.
Luckily, we do have another plugin called ShortPixel Adaptive Images that serves appropriately sized, optimized images from our global CDN. Here is the "How to get started with ShortPixel Adaptive Images" guide.