The recommended solution to this use case is to use respective issue hierarchy (e.g. Plans hierarchy) and inherit the Work type down from the Theme level in the hierarchy. That is possible if the work type is a single value selection field.
This documentation page gives example how to create an inherited custom field: Epic level custom field
You must put the correct value in the update_from_issue_key parameter. If you have the Plans hierarchy, the following value should work:
update_from_issue_key=jpoh_parent_4
Once you create such inheritted dimension, you can use this diemension in the report to count story points by the Theme level work type.
It is possible to create account-specific custom fields with the data admin access rights in the account. Please check this documentation link: Account specific calculated fields