The enumeration of particular powers by this Charter shall not be held or deemed to be exclusive, but, in addition to the powers enumerated herein or implied hereby, or appropriate to the exercise of such powers, it is intended that the City of Texas City shall have, and may exercise, all powers of local self-government, and all powers under the Constitution and laws of the State of Texas which would be competent for this Charter specifically to enumerate. All powers of the city, whether expressed or implied, shall be exercised in the manner prescribed by this Charter, or if not prescribed therein, then in the manner provided by ordinance or resolution of the commission.