The two previous games from the same developer - Divinity: Original Sin 1&2 - compares directly to it. Baldur's Gate 3 is essentially Divinity Original Sin 3 (but this time we have the D&D IP rights).

It's a slower paced game with tactical, turn-based combat.

Is this a game I can just play solo or does it require a party of actual people?

There is co-op, but the game works just fine solo.