If you shoot ultra-wide, you have to choose between extreme perspective distortions and tons of foreground to fill.
You can go for straight verticals and crop from below. That’s one option.
The second is to correct the verticals, but then you have to crop from the sides, and the top part of the image looks unnaturally extended. The result looks like having been taken with a longer focal length than it was, and the image looks slightly weird.
The third is to creatively work with the diverging lines, rotate the view and go crazy. That’s something I frequently do.
The fourth is to use foreground to fill the lower half of the image. That’s what I do here. Again, you can go low, like I did in the last image, or you can work with leading lines, like I do here.
If nothing else does, shadows frequently do the job.