dual wielding isn't TOTALLY trash in 5e. it flips flops back and forth between great weaponmaster for top damage. early game, dual wielding is better just due to action economy and low attack bonuses. i THINK at lvl 11 when fighters get their 3rd attack is when great weaponmaster pretty solidly takes the lead.
fighters will be the best dual wielders specifically because they get more attacks and feats than any other class. rangers are the only other class that gets the two weapon fighting style (which adds ability damage to your off hand damage). rogues thematically dual wield, but swashbuckler rogues (not in bg3) are the only ones that have any kind of mechanics for dual wielding. other than that any class can dual wield right out of the gate, there's just not much reason to. paladins could dual wield, for example, and do pretty well at it with dual smiting, but it doesn't normally fit the theme so no one does it.