Actually I am of the opinion, perhaps unwarranted, that Larian underestimated the scale of taking this project on and the popularity of the franchise, so in a sense they didn't have a proper plan. I don't believe they were expecting the large amount of EA sales, which I imagine led to the hiring drive and setting up new studios to enable them to tackle the scale of the project. The whole debacle with the narrative around 'the Box' is also suggestive of a lack of a clear plan. Just my personal interpretation of course.
Number of EA sales don't need to affect the scale of the project though. Like, imagine that EA got one-tenth of the sales and Larian went on to finish BG3 from there. The only guaranteed difference** between that hypothetical and what actually happened is that now they have 10x more EA testers, which turns into...bugs being found more quickly and maybe (optimistically) 30% more novel feedback suggestions. Sure, they'd also have 10x more money from EA sales, but that doesn't all
have to be re-invested into the project.
I could understand a line of reasoning that went: "Look at how many EA players are excited about our project! Let's hire more studios, developers, artists, etc so that we can create an even grander experience for these players. We have more funding so we can afford to increase the scope!" But doing this without a plan is worse than not doing it. Like...just save that money for the next game. Or DLC content. Make BG3 slightly grander, add a single additional companion and questline, but don't change the scope of the project partway through.
**Assuming that 1/10 the amount of EA sales is still sufficient for Larian to not actually scale down BG3.
