You’ll need to use something like Photoshop to “add sky” so that the overall aspect ratio is 2:1 … as per …
In Photoshop I increase the canvas size to create the appropriate ratio, then usually just fill with a blue “sky” colour.
I find that most assisted fills create strange marks, since they don’t complete the warped projection as it would be needed.
You can google for some 360 pano skies that you can blend in that look good as far as completing the sphere … but, unless you have loads of time to do all the blending needed, and knowing the pano was taken in a drone, they still look fake.