games

2's the only one that's a direct sequel, so you can start with 1 or 3. Overall the continuity goes 3->hundreds of years->1->2->thousands of years->Nier->tens of thousands of years->Nier: Automata.
I will warn you though, combat in 1 and 2 is a lot rougher and more repetitive than in Nier: Automata and Replicant 1.27whatever, and the world and story of Drakengard, particularly 1, is much darker and fucked up - grimdark fantasy kinda thing. The first game's "heroes" include a blood knight protagonist, his trusty human eating steed, a useless priest, a woman driven insane by the loss of her family, and a paedophile who escaped the massacre of his family because he was jacking off in the woods. It's not played for laughs, it's an extremely dysfunctional group of outcasts killing thousands of people to stop something worse than them from happening. 2 and 3 lighten up a bit on the heroes, but there's still plenty of weird sex stuff across them and the villains.

Overall, my advice is don't. Just read a Let's Play of them instead.