It's worth noting that the "scary" parts of the Outer Wilds DLC (are very mild, and) are not mandatory. That is to say, for the most part, if you find solving a part of the game too stressful, try approaching it differently.
I loved the base game and DLC. Should be the top of any backlog IMO.
I guess the level of scariness is subjective, at least from what I've read not everyone seems to agree that it's very mild :P But I'll definitely play it eventually, the base game is one of the best games I've ever played.