ERPNext
Adding modules that are not in standard image
To run erpnext with the Employee module included -you override values,see details for erpnext values (https://helm.erpnext.com/faq.html#how-do-i-customize-values-for-the-erpnext-helm-chart) and use an image that includes the module.
For HRMS module - its image resides here: (https://github.com/frappe/hrms/pkgs/container/hrms)
Example:
image: repository: ghcr.io/frappe/hrms tag: v15.41.0