If you want to automatically assign Roles and Permissions to users, you can do so using the Groups feature.
To do so, create a Group and once you're in it, click on ... beside Create a Sub Group and select Power User Settings.
In the new panel, click + Add Rule.
Use User Role dropdown field to select the Role that the users should be assigned, and use the checkboxes in the Datasets to assign their corresponding Datasets. You can add additional combinations of Roles and Datasets by clicking on + Add Another Rule.
Users that are enrolled in the Group will be automatically set as Power Users with your specified permissions.
This can pair together with Automatic Enrollments to automatically assign users with certain parameters as Power Users.