Through the admin portal a user who is a globe admin is a admin on the local pc that is on the azure domain.
However for better security you there are time in which you need to be a admin to use some software.
On the pc first login with the azure user account you want to add as admin.(this gets the User GUID to the PC)
Open command prompt as admin (you will need to enter your admin details) then type the below and click enter
net localgroup administrators AzureAD\username /add
for example firstname.lastname@example.org username is test31341
If you have azure connect replace Azuread with the domain that you are syncing