The Constitution does not “grant autonomy to the states”, several or otherwise.
The Constitution enumerates the powers delegated to the federal government.
No disagreement, but the scheme devised by the Founders, in practice, envisions the states, or in the language of the day, “the several states”, as autonomous entities, granting limited powers to the Federal Government in matters of foreign affairs and war, and running the Post Office, creating post roads, and regulating interstate commerce.
The whole damned camel is in the tent today, largely as a result of the Civil War, when the powers claimed by the Federal Government grew far beyond anything envisioned by the founders.