In the official EA version, ranks required online play. This repack often includes server emulators or tweaks that allow you to unlock all weapons (L85A1, G36C, DAO-12) even while playing single-player against bots.
This collection brings together the entire Battlefield 2 ecosystem in one package: Battlefield 2- Complete Collection MULTi9-ElAmigos
Installing this collection is straightforward, but because it is a repack from 2010s-era software, follow these steps for Windows 11/10: In the official EA version, ranks required online play