Can it be possible to choose either a stepper or a workflow based on the user privileges? So if the user is a data steward he has to go through a workflow where as if the user is a semadmin he can directly create a golden record using a stepper.

Yes, this is possible.

In the Action Set, you can create two 'Create' actions, one using the workflow and one using the stepper which you can set in the Actions Configuration properties tab.

For the workflow task which is assigned the DataSteward role, it means they will have to go through the approval process.