As of late 2023, Valve officially updated CS:GO to Counter-Strike 2 (CS2) on Steam. The legacy version of CS:GO is no longer available as a standalone, playable offline game through official means.
Counter-Strike 2 is your free, legal, and safe offline option. It is not identical to old CS:GO, but it is 95% the same gameplay for offline bot matches. Download Game Counter Strike Global Offensive Offline Gratis