it'd be an entirely separate app, not through the US app. you'll need to go to the actual korean lezhin site here to buy: https://www.lezhin.com/ko/comic/no_eurydice you'll need to make a new/separate account there, it's a separate site
(if you check in at https://www.lezhin.com/ko/arcade/attendance when the new chapters are up, you can usually just get them for free with the bonus coins! assuming it's the only thing you're trying to buy.)

I want to buy the latest chapter but can’t figure out how to on the lezhin app because im in the US :( even if i change the language to Korean