I like flying, but my car doesn't fly. Yet. For now, I'll have to get a plane. But maybe one day my car will fly...
Virtualbox 6.0.# is supposed to allow AMD/V (this is the AMD version of VT-x) to get through to a guest so the guest OS can use it to do things like Hyper-V, supposedly. Intel's VT-x can't pass through, yet.
You have an Intel CPU. This is the car that can't fly. So you need a host PC with an AMD CPU. This is the car that can fly. And even then, passing AMD/V through to a Virtualbox guest is in its infancy and experimental. Also prepare to have a slower third-level guest experience.
Or use VMware. This is the plane....