Four times in our nation's history a new state been carved out of a pre-existing state. Kentucky broke away from Virginia in 1791 and Kentucky was separated from North Carolina in 1794. Maine became a state when in 1820 it separated from Massachusetts, In each of these cases the new states had to receive permission from their state legislature and from Congress,
When Virginia seceded from the Union in 1861 many of the counties in what is now West Virginia did not want to secede. The counties wanted to separate from Virginia and form their own new state.
Because the parent state of Virginia was in a state of rebellion, the counties of West Virginia only needed the approval of Congress to be admitted as the thirty fifth state.
Today, California is in a state of rebellion. The government of California continues to violate Constitution and refuses to enforce federal laws. As a matter of fact, a ballot propostion to secede from the United States has been approved by the Secretary of State and is gathering signatures.
Because of California defiance, Congress has the authority to admit the state of New California without the consent of the legislature of California.