One can say that one of the most sought after addons for X-Plane 11 is realistic clouds.
Top name weather-related developers for X-Plane 11 such as, xEnviro, Ultra Weather XP, and others, all have come up with high-quality payware weather engines which display volumetric clouds amongst other features.
Developer BiologicalNanobot has developed a freeware product that replaces the default clouds in XP. The product has already received good reviews through the developers’ X-Plane forum. The product is called Enhanced Cloudscapes for X-Plane 11 which, as stated above, replaces the default clouds with realistic and volumetric clouds for extra realism.
This product is in the alpha phase and can be downloaded through the link provided above.
Compatible with X-plane 11.30+ and weather injection engines such as ActiveSky XP.