Have you ever tried to upload a WebP image? Some websites don't allow uploads of WebP images. In that case, you can upload WebP images somewhere else and use the URL from it.
There are lots of servers where you can upload images. We will use the website below, the simplest one to upload an image and use it.
https://catbox.moeJust go to the website, and drag & drop your WebP image. Once the upload is completed, copy the URL address by clicking it.
Now you can use the URL address using HTML tags as follows:
<img src="https://files.catbox.moe/xxxx.webp">Please keep in mind that the HTML tag won't work unless you set the editor to an HTML mode.