Dynamic Workflow approval for AoR based on user selection of a department

Summary:

Dynamic Workflow approval for AoR based on user selection of a department

Content (please ensure you mask any confidential information):

We have a requirement in which the employee need to raise a request, in this request he shall select a department, and this request should go for approval of the head of department (AoR) of the selected department.

So we have created a Document of Record and added a field named department as LOV with all the departments.

We need the DOR to go for the approval of the Department head of whatever department that shall be selected by the employee. We have almost 200 department, so we are looking for a kind of function that takes the department name and AoR type "DEPT_HEAD", and return the head of the department.