No, you have to be authenticated on the site where you want to create users.
The workaround MIGHT be to create a script that you use and you can choose the site. I haven't done it, but check out tabcmd Commands - Tableau for the createsiteusers and createusers arguments
AS Chris said it is not possible, you are authenticating only a particular site not all sites. As of now we dont have any option to add user like that neither via Tabcmd nor Rest Api's.
However, you can use other frameworks to authenticate other site by using same access token received from first call, in case user is having access to other site/sites as well.
Sajad Bhat wrote:
As of now we dont have any option to add user like that neither via Tabcmd
Did you read my post about the createsiteusers argument for tabcmd ? Why won't that work ?