Advice for a new player?

I started playing BG3 on release and I was enjoying it, even though I wasn't too familiar with turn-based combat (the RPGs I normally play are Dark Souls, Elden Ring, and Bloodborne). However, I got to a point not long after you go into that burning mansion where I was advised to level up more before proceeding. I ended up coming across the Phase Spider Matriarch and was getting absolutely destroyed. Even when I tried sneaking I'd get spotting, or if I tried knocking it off that wouldn't work. I felt like I was either not great at turn-based, my character build was bad, or it was a combination of both. Due to this, I haven't played it in about a year, but I really want to pick it up again.

I'd be getting through quests pretty well up until the point, so maybe I thought the only place to level up was the Phase Spider and if I can't get passed that, then I must've messed up somewhere.

Could someone give me tips on a levelling up? Are there other areas I should go to rather than the place I'm currently stuck in? If it's relevant, I remember turning karmic dice off for some reason. Sorry if I'm being vague. I was aiming to switch from Astro Bot to BG3 tonight, as I need a fantasy RPG to play and this feels like unfinished business!