The structure of 'Lore Olympus' isn't strictly linear, so a standard numerical order works but might miss some of the fun. The main story is told chronologically from chapter 1 onward on the Webtoon app, but Rachel Smythe sometimes releases bonus Fast Pass episodes like 'The Party' or 'A Day in the Life' that are set at specific points in the timeline. They're not essential for the main plot, but they add flavor and character depth. If you're reading for the first time, I'd recommend just following the official numbering on Webtoon; you won't be lost. The app separates the main episodes from the bonuses clearly anyway.
That said, if you're doing a re-read or want to get the absolute most out of the timeline, you could look up fan-made guides that slot in the bonus content. Some events, like Persephone's early phone calls with Hades or certain flashbacks, have a more emotional payoff if you read the bonus scenes in their chronological spot. But honestly, the series is designed to be consumed as it's posted. I tried a meticulously ordered re-read once and it was interesting, but it didn't radically change my understanding. The core emotional beats—the trauma, the romance, the bureaucratic scheming of Olympus—all land perfectly well in the default order. The art and pacing do most of the heavy lifting.
My only real 'order' advice is to maybe save the physical books for a second pass. The print volumes have some exclusive content and gorgeous art, but the weekly cliffhanger experience of the webcomic is its own unique vibe. Starting with the app gives you that community feeling of waiting and theorizing alongside everyone else.