If you look up gta vi free download, the verified details show the game is a paid release

https://wiki-byte.win/index.php/GTA_VI_free_download:_co_potwierdzono_o_premierze_i_pobieraniu

If you look up gta vi free download, the verified details show the game is a paid release, while only promotional assets like wallpapers and trailers are available for free.