Anyone who suggests 'The Shadow Cadence' is probably giving you the most common gateway recommendation, but honestly, I think that one's overhyped in terms of being an entry point. It's a massive doorstopper with a huge cast and a complex magic system based on harmonic resonance. New readers can get overwhelmed by the music theory metaphors. If you're someone who loves diving into deep worldbuilding right away, maybe it'll work, but if you're testing the waters with Jordan Walker's style, the 'Cadence' series can feel like a commitment. I bounced off it twice before finally pushing through.
Instead, I'd point you toward 'The Last Weaver of Greymist'. It's a standalone set in the same universe, but it's much more character-focused, following an older protagonist who's lost their magic trying to solve a mystery in a decaying coastal town. The magic is softer, the stakes are personal, and it showcases Walker's beautiful prose without the density of the bigger series. It's how I got my sister into his work. After that, you can go back to 'Cadence' with a better feel for his rhythms, or jump into the 'Iron Codex' duology, which is faster-paced and has a more heist-like plot structure. That one's a lot of fun and doesn't get mentioned enough.