Look up lists of the best hard scifi and you'll find the Remembrance of Earth's Past Trilogy, or at least the Three Body Problem, on almost every one.
Many readers come away from the first book stunned at how believable the technology feels compared to something like Star Trek or Star Wars.
I'll give you that the further the trilogy goes the looser the explanations get, but that's by design. We jump far, far to the end of the universe. How does anyone give a reasonable explanation for billion year advanced technology?
On the flipside, in the Expanse, humans are limited by physics and largely modern limitations, sure, but the crux of the story is built around a magical alien molecule for which we are never given an explanation. It's hard scifi to a degree, but no less soft than say, the sophon in ROEP.