The approach Stranger Things (at least, in the first, best, season) uses to suspend disbelief is to invoke a sense of child-like wonder, AND terror. Our protagonists are, by and large, children, or emerging from childhood into the lived body-horror of being a teenager. We see the world (primarily) through their lens, a lens that magnifies AND simplifies things. They don't understand what's going on, they just _know_ things are happening. Their credibility is established on the basis of "are these things a kid could conceivably think/believe."
Contrast that to media like Moonfall, where the characters are supposed to understand what's happening AND convey that to the audience. That's a much bigger lift. Their credibility is established according to "does this correspond to things an engineer would plausibly say/believe," which not many films get entirely right.
Stranger Things also has one more screenwriting technique going for it - it shows, instead of telling. We are _shown_ 11 being submerged into a tank and transported to the Other, we aren't told that that's whats happening. We are _shown_ the terrors of a mother who's lost her child, we aren't told "oh she's so sad." Show, don't tell, is THE big rule of storytelling, and it's ignored because it's hard to achieve.
EDIT for grammar