Create Two List,

Employee

and a List for the Departments Lookup Column.

Customize the Employee Form.

change the Department from textbox to dropdown.

Add a datasource to the Lookup list and add to the Departments dropdown.
EmployeeLookupDepartment.Title
Also sort it by Title.
SortByColumns(EmployeeLookupDepartment.Title, “Title”)

Also change the datacard
DataCardValue7.Selected.Result
DataCardValue7.Selected.Title

To make your dropdown start with “-” on new, set the card default from:

ThisItem.Department
to

If(frm.Mode = FormMode.New, “-“, ThisItem.Department)

If your list has a lookup column

to display item in a choice field use Items: Choices([@Submissions].ColName)

for datacard Update: colName_Choice_Val_3.Selected