How do you create a fluffy cloud in blender 2.82?

I'm not sure that this is a complete answer, but maybe what I found will help you. I also wanted to make such clouds

https://www.youtube.com/watch?v=lPAYX8z9i8M Creating Procedural Volumetric Clouds with Blender Eevee (48:35)

https://www.youtube.com/watch?v=GhMQN4vVMIU Create Procedural Clouds Fast (Blender Tutorial) (3:12)

https://www.youtube.com/watch?v=WJMol3CLHEE How To Make Clouds in Blender - Procedural Volumetrics (19:47)

https://www.youtube.com/watch?v=Nb1jQ9UsTAw How to Make Volumetric Clouds In Blender (2.83) (8:15)

https://www.youtube.com/watch?v=Br_ldLJPtxU Volumetric clouds in EEVEE - Blender 2.8 [ Beginners ] (12:07)

For water you can use Ocean Modifier and shader with "Glass BSDF" to Surface output with "Volume Absorbtion" to Volume output

Edited: I found this in reccomendations. He creating clouds from metaballs and then adding displacement with voronoi texture and other textures, using "Principlied Volume" for volume absorbtion material.

https://www.youtube.com/watch?v=5QxCa-bsbK0 Creating Fluffy Clouds in Blender (10:48)