That's what the difficulty settings are for. No joke. Nearly any trash build can cruise through the easy difficulties with no more than a basic understanding of how turn based combat operates, and you'll need to be a sweatlord with three spreadsheets open to reliably pose a threat to the hardest difficulty. Personally, I like to play in the middle but still overoptimize my party, so the early game is a challenge and then I just completely steamroll the final third of the game once we really get cooking with mythic levels.

If you already know DnD then you can play pathfinder with minimal confusion. An hour's worth of reading a couple good build guides will give you a good idea where the differences lie and why certain choices are commonly made (Point-Blank/Precise Shot feats for instance). If you don't already know DnD and you're coming from something like Pillars of Eternity or Divinity Original Sin, you might have a little bit of a rough landing. But that's what a wiki is for, or just straight up following a build guide if you're timid.

That's a fair assessment. There are a ridiculous number of classes and subclasses each with their own quirks. And that's without getting into multiclassing or Wrath's mythic path system. I've definitely spent 20+ minutes leveling up before.

Do you like JRPGs? Yakuza: Like a Dragon is fairly recent and has a sequel (that I haven't gotten to play yet). The story is NOT your typical RPG fare, it's a modern drama about an ex-gangster trying to get back on his feet after prison (it gets emotional, I cried). But the combat is a classic turn-based RPG and it's fun, stylish, and just barely complex enough to stay engaging.

Pathfinder also has fairly detailed difficulty settings panel, you can tailor the difficulty to your liking. Story mode difficulty and auto level up presets makes the game beatable for even your grandma, so you can ease into the system.

There are also some great guides out there for different builds for both companions and main character.