Other games of the genre have difficulty adjustment settings that allow you to tweak things like that (pathfinder and solasta both have a level of granularity in this regard, with pathfinder having more overall, though both let you nudge dice rolls for or against players at a general/universal level if you want). Larian's game does not have this in any decent way, sadly - it has its three difficulty modes that are fixed packages locked out of adjustment, and to a certain extent the game mocks and insults you for choosing a difficulty that favours you. It's like the sweaty dm that says "Oh, you'd like the dice to favour you a bit more? Oh, I guess you need the easy game for babies then, baby, here you go, here's the easy baby game, where everything falls over in one hit and the enemies are dumb and have no weapons! Oh, but because you're such a baby who can't play the game well, I'll lock out a bunch of your customisation options too, wouldn't want to confuse the little baby now would we? can't have you trying to customise your character and maybe messing up! ha, ha, ha, ha! That's the game you want right?" Sorry if that seems cynical - that was my impression of how the game acted when I changed difficulty settings and saw what it did.
You can work around that because you cna change difficulty on the fly at any time, so, you can turn the difficulty up when you want to, for example, multiclass your level up (something locked out by being on the lower difficulty), and then put it back to story mode when you've done your customising... but the fact remains that you've got to *work around* this 'design choice'...