If the optional plan, including an additional option or options as provided in section 3091 (relating to designation and applicability of plan), is approved by the voters, the county shall be governed by the provisions of the subchapter providing the basic optional plan and by the provisions of Subchapter F of Chapter 29 (relating to general provisions and limitations for optional plan municipalities) and Subchapter A of Chapter 31 (relating to officers and employees), except that the elected sheriff shall be subject to the provisions pertaining to that office as provided in this subchapter.