I've never been a big fan of the clouds in the Chapters 4 & 5 TODMs, which are the only ones we can use in UEFN. I decided to take a look into how Fortnite did their clouds originally and adapted them to work as a single material on a big skydome mesh.
If you want to use this, make sure the mesh is positioned at 0, 0, 0 and that you scale it up to 280 on every axis! Then make sure you rotate it so the clouds fade at the right spots during the morning and evening, I recommend changing the "Fade Horizontally Offset" parameter during this process so it's easier to set up.
I strongly recommend using the Chapter 4 TODM with these, then put down a Day Sequence device and make the cloud's opacity in there zero.
Preview of different times of day.
Click on the text above to download, if that doesn't work:
https://drive.google.com/file/d/1vfA1mgzj2G_5NtQaThKuhldZO2k0BU3G/view?usp=sharing