Many customers have asked me in passing when Windows LAPS will be supported for managed devices joined to an Entra AD Domain Services domain (formerly known as Azure AD Domain Services). All I can share for now is that the owning team is aware of this ask and it is in their backlog. Please up-vote this feature to add your support!
It would also be helpful if you are willing to PM me with your company name and the # of EADDS\AADDS devices that would be Windows LAPS-enabled once the support is available.
Overview of Microsoft Entra Domain Services - Microsoft Entra ID | Microsoft Learn
thanks,
Jay