That is absolutely not a free feature on Steam. Some publishers like Paradox leave old versions as ‘beta’ branches to allow us to reinstall them, but Steam as a whole is very against you playing anything but the latest version.

You cannot instruct Steam to not update a game. When you launch a game, Steam will update regardless, unless you have gone offline, or you launch it in a way that bypasses the Steam client. If you ever forget to go offline before launching a game, Steam will forcibly update it