WordPress creates image size variants based on resizing images on posts?

How to Dynamically Resize WordPress Image On-The-Fly On View without creating additional file? How to resize WordPress images on upload to specific height and width without cropping it? I need the image to be “contained”.

When a user uploads an image, WordPress will generate as many images as you’ve declared with add_image_size().

There is one important thing to note. WordPress does its resizing on upload. You will need to regenerate those images or re-upload the image for it to work on those already on the site. 

How to make WordPress images responsive without creating the resized copies?

WordPress why do my image have a srcset? I only upload a single image.

When users with thousands of images back up their websites, they may find that their backup has become very large and takes more time to complete. Other users find that they don’t use some image sizes at all, and disabling them will save storage space.

When you have an image sitemap, each image in each post will be displayed in the sitemap per post, so the chance to see the posts when searching for images is pretty high.