They can be reasonable but often aren’t as accurate as a true IQ test which is conducted using many more tests such as spacial relations and pattern recognition components. I have never seen a good on line one that includes those things. The on line ones are usually just knowledge based and that is only part of a true IQ test.
I see a lot of them online that are not only just knowledge based, but limited to one subject. My understanding of IQ is that it’s more about concepts than specifics about people, history, etc
