Games from 2K on Epic use whatever setting your Operating System (OS) Language is for in-game display for Voice and Text.
Here is how you can change it through the Epic Game Store Client:
- From the Epic Game Store Client, at the bottom left, select “Settings”
- Scroll down to the “Manage Games” option near the bottom of your settings and expand the entry title of the game you are looking for (ex: "Borderlands 3")
- Check the box under “Additional Command Line Arguments” and then apply whichever supported language you want.
Brazilian Portuguese: -culture=pt-BR
Simplified Chinese: -culture=zh-Hans-CN
Traditional Chinese: -culture=zh-Hant-TW
Keep in mind that some languages in some games will only be able to change the text, not the voice language.