Shadow and Bone's world-building got me back into fantasy a few years ago. If you're chasing that feeling of a fleshed-out, slightly harsh world with a unique magic system, you should absolutely check out Leigh Bardugo's other series, 'Six of Crows'. It's set in the same universe but in Ketterdam, and the world feels so much grimmer and more lived-in. The magic is less central, but the trade routes, gangs, and political maneuvering create this incredibly dense atmosphere.
For a different flavor, 'The Poppy War' by R.F. Kuang has some of the most intense and brutal world-building I've ever read. It's not a hidden magical land; it's a fantasy version of 20th-century China, and the way the gods and shamanism weave into the historical parallels is mind-blowing. The magic system is devastating and costs the characters everything. It's a much heavier read than Shadow and Bone, but if you want a world that feels real and consequential, it's unmatched.
Some people recommend 'Mistborn', and it's fine, but the world always felt a little more like a puzzle box to me than a place. Ketterdam and the Empire in 'The Poppy War' just stick with you longer.