When you enable Webp support on your ProcessWire site, it only creates WebP versions of variations. To create them of your original images as they are added (which I recommend to improve front-end performance), add the following hook to your admin.php
page.
wire()->addHookAfter('InputfieldImage::fileAdded', function(\ProcessWire\HookEvent $event) {
$image = $event->argumentsByName('pagefile');
// Simply calling it will create the image; nothing needs returning
$image->webp->url;
});
