Tennessee Code Title 5. Counties § 5-1-202

(a) After adoption of a charter pursuant to this part, no right, power, duty, obligation or function of any officer, agency or office of such county shall be retained and continued unless this part or the charter of such county expressly so provides, or unless such retention and continuation be required by the Constitution of Tennessee.

(b) The adoption of a charter shall not have the effect of removing the incumbent from any county office or abridging the term or altering the salary prior to the end of the term for which such public officer was elected.

(c) No charter, whether existing or adopted after May 22, 2019, may be interpreted or amended to alter, amend, or reduce the duties, qualifications, or privileges of the constitutional county offices of sheriff, register, county clerk, assessor of property, or trustee in a manner inconsistent with the laws of this state; provided, that a charter may increase the duties of such offices in a manner consistent with the laws of this state. This subsection (c) must not be construed to affect the terms of the constitutional county offices of sheriff, register, county clerk, assessor of property, or trustee.