You cannot extract Part 12 without having Part 1 through Part 11 (and any subsequent parts) in the same folder [1, 2].
Since it's "Part 12," there's a sense of a long, unfolding narrative or a massive amount of hidden data. Concept: The Digital Fragment riz.part12.rar
RAR volumes usually follow .part01.rar , .part02.rar , etc. If you’re missing even one, the whole "deep" archive remains locked [2]. You cannot extract Part 12 without having Part