Let's be realistic, nothing is necessary in the game unless the law says otherwise. Since most games try to sell worldwide, they should respect both country specific and international law. We have our right to express opinion on certain matters, but we can't expect the company to follow through. I guess, consumer holds some power over the developer, especially nowadays when the company can be 'cancelled' for unintentionally mistreating some group's trauma. A disclaimer should work well to cover for those risks, I only see it as a net positive. However, I won't like my game pausing here and there to ask me if I am okay with something or not. This is poor QOL. All this stuff should be known in advance as a separate warning or should be clear based on maturity rating.
I agree with this. Back during EA there was a warning on Steam, before you could buy the game, which I thought was enough. I don't know, if it was still there with full release, but I would think so.
A disclaimer should work well with covering everything. I know that people with specific phobias often ask in the community ( most common for fantasy games are spiders) and in my experience receive detailed description of the scenes, where the fears objects/ things do occur, so that they can decide, if they can put up with it or not. For the more heavy stuff, I think the rating and a disclaimer ( which Larian has, I think?) would be enough.