I've had a student here use Microsoft Edge to visit Bing.com and search for inappropriate adult-themed images. The search returned page after page of some very explicit images. Because the student didn't visit any actual adult sites, our web filters didn't block the images. 

I've found ways to control search results in Chrome and Bing, but not in other search engines. Short of blocking the domains of other search engines, I'm not aware of a way that I can block everything. Have any of you fought this battle?