While the base simulator is a free download, the DCS: Flaming Cliffs 3 (FC3) module itself is a paid expansion pack . You cannot download FC3 for free legally; however, there are several free ways to experience its content or enhance it if you already own it. Getting Started with DCS for Free
In February 2024, Eagle Dynamics released a free texture upgrade for FC3. This includes refreshed Physical Based Rendering (PBR) textures for the cockpits and external models of the F-15C, A-10A, Su-27, Su-33, and J-11.
You get the Caucasus region and the Mariana Islands for free. Free Upgrades and Mods for FC3