If the ceiling is white I’ve used a homemade light scoop. I’ve only used it on ceilings that are lower (8ft) so I don’t know how it would work on higher ones. I power up the flash as high as it can go (+1) and it works Great!
When I found this out it was so exciting. I can take nice inside pictures without spending a penny. But half of our house has wood ceilings so I have to figure out something else for that.