Hi,
Thanks for your posting but please note this is tech forum with English support. I have translated your question with Google but kindly correct if any misunderstanding.
1.As for limitation on use or server software, please check details in below screenshot or download the relevant Product terms.
2.For domain controller in essential 2019, there is not many details but statement as below:
Windows Server 2019 Essentials has the same licensing and technical characteristics as its predecessor, Windows Server 2016 Essentials. If configured as a Domain Controller, Windows Server 2019 Essentials must be the only Domain Controller, must run all Flexible Single Master Operations (FSMO) roles, and cannot have two-way trusts with other Active Directory domains.
Reference link:
https://cloudblogs.microsoft.com/windowsserver/2018/09/05/windows-server-2019-essentials-update/
Thanks,
Jenny