Use the launcher (Steam/GOG) to download the core files.
If you are looking for a free experience, Call of Duty: Warzone is the official free-to-play battle royale title available on the Microsoft Store and other PC launchers.
You can buy the original Call of Duty (2003) on Steam or GOG . The expansion, United Offensive , is typically sold separately or as part of a bundle on these platforms. Call of Duty Deluxe Edition Free Download (Unit...
The expansion pack featuring new missions and vehicles.
Buy the game from Steam or find a physical CD copy. Use the launcher (Steam/GOG) to download the core files
The original "Game of the Year" version.
Ensure United Offensive is installed to the same directory if you want the full Deluxe experience. The expansion, United Offensive , is typically sold
There is no legal "free" download for the full original Deluxe Edition. Beware of "free download" sites, which often harbor malware or pirated content.