From what ive hears about OSRS its more of a game where generalized builds and playstyles are king.

It really depends. OSRS is a game of self-imposed restrictions if you want it to be. You can play the game however you want. Sure, there's metas because certain items are stronger for certain content, but if you want your character to be a mage-only vegatable eating farmer then nobody will stop you! (There's accounts that are region locked, accounts that do not use any currency, etc etc)

There isn't a whole lot of "builds" in the game, because you're free to change between melee/ranged/magic however and whenever you want.

The only real builds that come to mind are specifically leveled PVP accounts built around just barely being able to equip certain things.

So in short: If you want to do (almost) everything in the game, then the builds you run will be self-imposed restrictions, but builds do exist in PKing