How can we create a custom template for a dropdown virtual field, replicating OOTB behavior

Summary: We need to add a field-level on-change trigger to a virtual dropdown field, but are unable to do so using the out-of-the-box (OOTB) template. We're seeking guidance on creating a custom template that replicates the OOTB dropdown population logic while enabling an on-change trigger.

Content (please ensure you mask any confidential information):

• Requirement: Implement a field-level on-change trigger for a virtual dropdown field.
• Current Approach:
  • Currently using the OOTB template to populate the dropdown values, but the template doesn’t allow us to add a field-level on-change trigger.
  • Due to this limitation, we are attempting to create a custom template for the dropdown field.