It looks like you're referring to GTA V update 1.67 / 1.68 (common versioning on consoles like PS4/PS5 and Xbox, or modded PC setups). Here's how to install them depending on your platform:
Priority: High
Rockstar Launcher: Go to Settings > My Installed Games > GTA V and click "Verify Integrity" to force the launcher to check for missing 1.67/1.68 files. For PlayStation 5 and Xbox Series X|S Highlight the GTA V icon on your home screen. Press the Options (PS5) or Menu (Xbox) button. Select Check for Update. grand theft auto v gta 5 update 167 168 install
Released in June 2023, this update shifted the focus to aerial combat and massive Quality of Life (QoL) changes. The addition of the Mammoth Avenger It looks like you're referring to GTA V update 1