Question: Do people who sing with lots of power have a smaller vocal range? I have heard that if one sings with power, eg like an opera singer, you will get a smakler range. I feel that the more power I use the harder it is to sing higher.
Is there anything ti this?

Answer: 
Based on my listening experience as well as first-hand singing, I would say there's no correlation between "limited range" and "power". 

On the contrary, it's common for some singers to need to appeal to increased air pressure to reach the upper end of their vocal range (think of songs you can remember in which the singer belts a "high" note, which very often is accompanied by a surge in "power"). So if anything, I would answer "no" to the question.
No they don't. This is a bizarre claim, and if the person who made it has evidence - let's hear it!