I can lay out the broad strokes here so you know what to look for. After you’ve done some work, if you get stuck, come back with a specific question. It’s so much easier to discuss focused questions and work-in-progress on a forum.
The stones look like AI-generated images. If you want to make them from scratch, that’s a job for a full 3D package like C4D or Houdini or Blender, not Ae. You can make a 2D image feel like a 3D space by setting up what’s called a “camera projection,” and then animating a new camera through the scene. Some of the waves look like distortion effects (start with Turbulent Displacement); others look more like real footage that’s been composited in. The dolphin-shaped clouds can be generated by Ae, painted by hand in Photoshop and brought into Ae with layers to animate, or generated by particle systems like Trapcode Form using custom layer maps.
If there’s a lot of this on TikTok, it’s possible there’s a specific tool that makes the work easier than doing all the compositing in Ae. Look up “cinemagraph” software if you’re looking for an easy button.