Working at Microsoft as a Windows Virtual Desktop Global Black Belt, a couple of question that I often get asked is "what Active Directory topologies does Windows Virtual Desktop support?", and "how does the user login process work"? This article should hopefully answer both for you.
The TL DR answer is that WVD does not impose any specific Active Directory topology requirements of its own, and will work in any supported topology that you have deployed. However, there are some things that you need to consider when designing a WVD deployment.
As it stands today, access into the Windows Virtual Desktop service and onto the WVD session host, requires authenticating firstly against Azure Active Directory (AAD) and secondly against either Active Directory (AD DS) or Azure Active Directory Domain Services (AAD DS). In addition, there is a service called the "Identity Matching" service that ensures that the actual user is the same person logging in at both points.
The highest level requirement is that the user accounts need to be in both AD and AAD.