Bulk Permissions to Power BI Report Server

We have a number of users who have historically created reports on PBIRS on-premise (January 2023) with SQL 2019 as the backend Database however the permissions granted to the reports were best described as 'Mixed'.

We would really like to push a default set of permissions for an AD Group to all reports on the server however I am unable to locate any details on how do to this.

Is there any advice