There is no doubt in my mind that Larian knew what they were doing with the Minthara sex scene + the 'under construction signs over the other companions giving a certain impression of the game prior to launch. Certainly the Halsin/bear scene was there to generate buzz/controversy right before launch. The game was very much marketed with a 'sex sells' attitude-it feels very intentional even if they didn't outright state it-can't fault Larian for their marketing savvy-they ran a slick game in that department, at least.
Now I don't think that the sexualization in BG III necessarily translates into maturity though. For all their promotion of the sex and relationship side of things, I don't think Larian has really crafted an experience where the relationship experience is anything revolutionary or handled with any more nuance than the Lion's share of rpgs out there that tackle such material.
Polyamory with Halsin is ofc handled very poorly as the discussion in that regard is ample testimony to. The relationship with Lae'zel transitions to a conventional relationship whether or not you wanted to IIRC, and Minthara basically drops the drow relationship power dynamic she exhibited when you first meet her immediately after you get her back which might be unfortunate if that appealed to you.
