I would imagine they'd include some kind of difficulty option, at least in the final release. The game difficulty actually feels pretty nice for myself, but there are some instances when the fights are a bit hard and I've had to try again a few times. It's good in my opinion that there are also very difficult fights in the mix, especially in situations where combat isn't the only option.
There might be some hope for gaming with lower end computers in the form of AMD's FidelityFX, as AMD already lists Baldur's Gate 3 as something they'll support in the future. Don't have any real idea how big of an impact on performance it will give, but maybe you should check it out when it comes out for BG3.