I didn’t see a ton of the water from the video, but it mostly looks like they’re using basic water planes. The large wave at the end actually looks like a 3d mesh with a water shader applied. That being said I would think just about everything shown can be easily replicated.
Unity has some water prefabs in their Environment package (Assets>Import Package>Environment). There’s one that includes things like sea foam and some subtle waves. You could use that as your base. For creating the splashes, you could use a particle system so that when it detects the water you play a water splashing particle effect. The drops of water on the screen are done using a shader like this: https://assetstore.unity.com/packages/vfx/shaders/fullscreen-camera-effects/rain-drop-effect-2-59986
I’m not entirely sure how that big wave was created but I’m going to assume it included some sort of mesh deformation. If you wanted to buy an asset that cover all your water needs you can find a few like this: https://assetstore.unity.com/packages/vfx/shaders/suimono-water-system-4387
Water is typically created through fancy shaders so depending how complex you want your water to be will determine if it’s worth building something on your own.
Oh I forgot to mention, you could watch this course to see how the built in water prefabs can be used: https://cgcookie.com/course/fundamentals-of-terrain-generation