I don't even know if this is possible because I can't find anything anywhere about it but are you able to specify the groups that are added to the Local Administrators group during a domain join? like in addition to Domain Admins. I know I can do it with group policy but sometimes that isn't fast enough, right after a domain join the second group isn't always added which forces the techs to have to log in locally with admin rights and specify their domain account to connect to a network share in order to install software required by that PC.
The GPO is the way to go. You could do a gpupdate /force or you could do a reboot and have the computer GPO reapplied.