Larian (baldurs gate 3) is massive for being indie. I think where your misconception comes from is the term indie. The term comes with a lot of predetermined expectations and definitions, but in spite of this fact very large studios can be indie.
Of course it feels weird to label a studio as large as larian indie when compared to the likes of supergiant(hades) or two brothers of bay 12 who created dwarf fortress. None of the three are technically any less indie, but one certainly feels more indie, doesn’t it?