#524 changes the default behavior of the WebP Uploads module so that it only generates WebP by default, following the core decision, as that is a safer default.

However, the module still offers the alternative approach of generating both WebP and JPEG files. At a high level, this comes with the following tradeoff:

• Pro: Better backward/cross compatibility since any use-case where WebP is not supported can still leverage an equivalent JPEG.
• Contra: Large filesystem storage needs, since now every size requires two files, effectively almost doubling storage requirements.

While for a WordPress core implementation this decision would likely not be exposed as a user-facing control, for this plugin it makes more sense. It also would be applicable if WebP became a "canonical plugin".

Once #524 has been implemented, we can proceed with this one. It could work as follows:

• A new WordPress setting is registered to control whether to output both WebP and JPEG (e.g. generate_webp_and_jpeg), which could be a simple boolean value.
• If that setting is true, the default value of the webp_uploads_upload_image_mime_transforms filter should be changed so that it outputs both image/jpeg and image/webp for both image/jpeg and image/webp input format (effectively the same as it was prior to Modify WebP default behavior to follow latest decision (generate only WebP for JPEG) #524).
• A UI control (checkbox) for the setting could be added under "Settings > Media" in the "Uploads" section.
  • Label could be Generate JPEG files in addition to WebP
  • It would be good to add a brief description below that explains the tradeoffs, e.g. Enabling JPEG in addition to WebP can improve compatibility, but will effectively double the filesystem storage use of your images.