You probably won’t need to play the originals but they’re still worth playing. IIRC they’ve been refreshed/updated to play well on current resolutions.

Pillars of Eternity is also really worth looking into, it plays similar to Baldur’s Gate and it’s very open-ended. A lot of significant events in the plot are dependent on player’s choice during dialogue and prompts, and a lot of options are dependent on having enough attributes - for example, you might need to try to save someone clinging on the edge of a cliff, and using a rope is an option, but if your Might is high enough you might have an option to grab a tree branch to hold out for them, but choosing the Might option might lead to the branch breaking, that character dying, and making some future side quests available or unavailable. Lots of decisions like that so every playthrough is going to be a little different in terms of which NPCs are available and where you set off to in order to progress the plot. Super awesome game. Edit: there are also achievements for playing through without dying or playing without anyone else on your team, so it gets pretty sweaty, trying to talk to NPCs that may aggro you if you say the wrong thing