The .rar extension indicates a compressed folder that requires software like WinRAR or 7-Zip to extract.
This patch added content inspired by the Cyberpunk: Edgerunners anime, including new weapons, a transmog system (Wardrobe), and cross-progression. Cyberpunk.2077.v1.6.GOG.part04.rar
Storage: 70 GB available space. Additional Notes: SSD required. Cyberpunk 2077 on GOG.com including new weapons