To access the Cloud Tops, you must first acquire the Ocarina of Wind. This item is typically obtained after completing a series of Kinstone Fusions with the various Wind Crests found throughout Hyrule. Once you have the Ocarina, stand on any activated Wind Crest and play it to summon a tornado that will whisk you away to the sky.
The Cloud Tops consist of several floating islands connected by invisible paths and jump pads. You'll need to use your Roc's Cape extensively to jump between islands. Be mindful of the strong winds that can push you off ledges. Explore thoroughly, as there are many Kinstone Fusions and Heart Pieces hidden among the clouds. Your ultimate goal is to find the entrance to the Palace of Winds, which is often obscured or requires a specific sequence of actions to reveal. The journey through the clouds is a test of your platforming skills and observational abilities.