Further, how are you going to make it feel natural for a barbarian and a wizard to say the same lines the same way?
The same way games have been for literally years, including Larian's prior titles?
Allowing options of different types of voices which will come with their own styles of dialogue (Usually having something like a "Rough" voice for your gruff Barbarian/Fighter types, your well educated noble voice for your Mage types and some sort of sly roguish voice for your Rogue/Ranger types)
Or, better yet, incorporate Solasta's personality selection. Allowing you to tune a voice/dialogue to specific archetypes (I.e. Sarcastic, cocky, aggressive, shy etc).
DA2 and DAI get around this with differing tone options and making background more significant than class, but in BG3 we have so many classes and possible backgrounds. Just by virtue of those, you create too many possible personalities to create a voice for.
You act as if every particular pairing of class and background needs a singular unique voice.
While in reality, the only thing that is necessary is voices to match backgrounds. Just because someone is a Wizard, doesn't mean they suddenly developed a "Wizard" accent. Dialect and accent is determined by background, not class. The only thing that is class relevant, is the class specific dialogue options which is a simple as having whatever VA is doing the lines for the chosen voice option, to record those class lines too.
So if there's a scholarly voice type, it will work for anyone who has a scholar background (Or is roleplaying a character that has received an education, such as a Noble or even an Acolyte) - This can be for someone's Barbarian just as much as a Wizard, depending on how someone is roleplaying their character (For example, if I decided I wanted to play a Barbarian who was a noble that received an education but just happened to develop rage powers, I can opt for a suitable voice. Just like I could use an aggressive voice for a Githyanki Wizard who was raised as a warrior)