szone you could give a try to https://github.com/rosell-dk/webp-express since wordpress does not have native support yet without modifications.
Also this is not really related to aapanel much, it is a issue or a problem you will have to dig yourself a bit, since thats what we sysadmins do always. Own research is best, a simple search on google for "nginx webp wordpress" should provide articles and modules to help you achieve this. You will need to map the files in mimes so that nginx knows abotu webp, and then all would be good, or you could learn about pagespeed, that will automatically serve webp where is the case without additional wordpress modules. In fact I am testing myself pagespeed now, just that the process is long and vigurous since a lot of variables in place to learn and to addapt all to my website needs.