To give additional options, because Stephenson and Sanderson aren't everyone's cups of tea (producing insanely large tomes like Reamde, Cryptonomicon, and the Way of Kings), you may also consider the following, which are either hard scifi (requires few, if any, scientific discoveries we currently lack), speculative SciFi (requires one or two unexplained leaps of scientific advancement, but thoroughly explores the mechanics and consequences thereof), or speculative fantasy (any magic system is internally consistent, operates in particular ways, and the interactions between them are explored)

1. Adrian Tchaikovsky, creator of the most - realistic alien species in literature: Children of Time Series (Spec. SciFi (but only barely), Tyrant Philosophers Series (Spec. Fantasy), and an insane number of standalone stories among the three genres listed above, such as Alien Clay, Shroud, and And Put Away Childish Things
2. Dennis E. Taylor, for those with crippling reference-itis and enough of a science background to want the author to regularly presume the reader's knowledge of plate tectonics and special relativity: Bobiverse Series (Spec. SciFi, but only because of "subspace" and optoelectronics), Outland Series (Spec. SciFi, because the portal's function is never explained)
3. Andy Weir, who makes every book a high-school science class (in the best way) with a plot: The Martian & Project Hail Mary (Both Hard SciFi, and I'll fight anyone who tries to claim that the astrophage makes PHM speculative), also, several short stories, including The Egg (Spec. Fantasy) and James Moriarty, Consulting Criminal (Historical Fiction/Mystery)
4. David Mitchell, who is like if James Michener wrote historical fantasy: Cloud Atlas (Historical/Speculative Fiction), The Thousand Autumns of Jacob de Zoet, the Bone Clocks, & Utopia Avenue (all Historical Fiction with Minor Fantasy Elements)

If you want something more in line with YA, but with hard magic systems, consider "The Will of The Many", by James Islington, or "Sufficiently Advanced Magic" by Andrew Rowe.

I agree and I’m not the biggest fan, but it does get much better if you can get through the first half of book 1.

I appreciate that hot take. First books, IMO, tend to be more formulaic. I'm currently reading and on book 5, and there's been a number of times the author's used strong vocaublary or literary devices that I've appreciated. The feel of the series has certainly made some adjustments, and it makes sense considering he's at six and change years writing it at this point.

Ready Player One is kind of a good comparison; both in that case and in this one, my expectations were pretty low, but I enjoyed reading them. My reading list is mostly populated with nominees and winners of the major SF&F awards, but I decided to read this one based on recommendations from folks here in Lemmy, and because of folks I talk with a lot online (I play wow classic). I wasn't really expecting it to be amazingly well crafted, but I still maintain is silly fun.

DAMMIT DONUT!!!