Grant administrator permissions to local user without adding to administrators group

I need to grant administrator permissions to a local user without being member of the administrators group. This on windows server 2019

Solution 1:

What you're asking is impossible. Windows server and client builds operate with very well defined permission sets based on local groups. There are certain things you can work around without having full administrator rights, such as granting NTFS permissions to allow users to write in places that generally require administrator rights; but the ability to do things like installing applications and passing UAC prompts are going to require access to an elevated account.

You can either create a service account and place that in administrators using it where necessary; or have a user with administrator privileges do an action on the user's behalf. If this is a domain connected server then you should be using group policy or other tools to manage your local administrators group and avoid putting user accounts directly in it, use groups where possible for scalability.