Technically almost every MMO on the market these days is pay2win, including WoW. There is, however, an argument to be made about the extent to which you can get an advantage, and how much that advantage actually matters. Lost Ark lets you progress slightly faster, or give you access to convenient tools like more Bifrost Slots, but all of those you can still get as a regular player. In order to sufficiently speed up your progress, you will always rely on other players to provide the materials you want to buy, and you will have to spend a few thousand bucks to get meaningful benefits (with EU central AH numbers, youd currently have to spend close to 2grand to gain 20ilvl, or just wait another day or two and do the same).
PvP is normalized/structured, so there is no P2W there, unless you care about Guildwars, where it matters maybe 2%, and no one cares about Guild Wars in LA.
As for PvE, the high-end content is also normalized (meaning you get scaled down if your ilvl is too high), so having higher ilvl doesn't actually improve your character. It is nice for bragging rights, though. A lot of content is scaled and you will have little issue getting to the required ilevels for the highest end content just by playing the game. Unless you're spending tens of thousands, you wont get there faster (and then you'd be playing by yourself) and you will still be lacking a variety of other character improvements that are needed, that you cannot buy., like Skill Points.
Overall, LA is one of the games where P2W obviously still exists, but it won't give you a meaningful advantage over others that play regularly. The only noticeable benefit to P2W would be if you're only playing the game for an hour or so every other day, but at that point, why do you care about whether someone else gets to a certain breakpoint or new content slightly faster than you anyway.