This film is trying to be a Thor movie so damn hard that it almost succeeds... but only if you're comparing it to Thor: Love & Thunder. I mean, look at what it's packing: brothers that are bitter rivals learning to bond and become more of a family; wise-cracking insectoids; alien (or as good as) races, including a wise-cracking bruiser friend that keeps losing limbs; kidnappings and kids in danger; comedy mounts; a main hero that revels in the whole "having no plan is the plan" style of quipping. Yeah, there's a lot of overlap. That is, when they aren't ripping off other Marvel franchises; the film literally ends with him saying on live television "I am Aquaman!", which is a choice, for sure. (I also had to cringe when DC repeatedly referenced Marvel movies and characters, whilst largely overlooking their own stable of ideas ‒ come on guys, your films suck, but the rest of what you do is still beloved, you can reference some it!)
Though, to be fair, The Lost Kingdom sticks the landing a little better than Love & Thunder (though, to be fairer, the Thor-based option had a much better villain and overall backstory). Also, much like the first film, the world building and lore around Atlantis is great throughout, as are the designs of these underwater civilizations. Heck, even the forgotten "evil" kingdom is an interesting idea, and I really enjoyed the cannibal fish men of the Sahara, even if I don't fully understand the logic behind how they're able to survive on blood alone 😅
On the other hand, the film has a weirdly anti-science stance towards climate change. They acknowledge that the "surface dwellers" are fucking up the environment, but also then immediately minimise this by pointing the finger at greenhouse gas machines that are being used to accelerate the melting of the ice caps so that the Necroking and kin can rise again, which is all a bit confused.
Overall, then, the film is fun enough, very predictable, and often quite pretty to look at, but it's also a weird mishmash of ideas poached from better movies.