For WEBP you can use Dianoga,
But there are currently some issue with the WEBP support, see this issue: github.com/.../43
that is in the current 4.0 release,
already fixed, but not yet released you can create your own build. from the latest source, but that contain this bug: github.com/.../49
so have a little patience before it works well. currently I can't say WEBP is supported.