Can i still increase IQ at age 30 is that possible, let say you read or do complex problem can i still increase IQ if i am 30 or 25 years old?

Your IQ is really measured by how much information you can hold... not measured by how much information you know (even though that is what everybody thinks)
So when you read or do complex problems it expands your brain and yes technically helps your brain get used to holding more information
So technically the answer is yes

How do we if it is a video and they know your face.