Since there is not an overall difficulty slider to 5e as there will be in BG3, how would you suggest making encounters easier and harder?
*Points to the difficulty settings in BG 1 & BG 2*
Use those. I mean this is supposed to be the third game in a trilogy, don't need to reinvent that wheel.
I don't think that will work in 5e. There isn't a way to out scale hits with AC like there was in 2e. BG1&2's main difference was more damage when hit but in 5e It's not even a matter of a completely min maxed character; you just aren't given the tools to prevent the hits, or guarantee them. You would just die from the increased damage on ever hit. I don't even think spell failure is in 5e, casting or copying scrolls, and that was another annoying trait of the difficulty slider.