I only ever played the first 2 until I got a PS5 that came with Ragnarok.
They're not even the same game anymore. The originals were more akin to Devil May Cry while Ragnarok felt like it could have been an Assassin's Creed game.
I can't say much for the story since I haven't gone very far in Ragnarok (and only beat 1 and 2 back in the day so my memory on details is a bit hazy) but the game play is definitely a lot different than it started.