So if the Feds raised the rate to 25% what would happen to GDP? If the Feds lowered the rate to 0% or went negative what would happen to GDP?
I'd ask you to answer your own questions. What do YOU think would happen?
You might see GDP go through the roof in the first scenario, but it would all be illusory growth because inflation would destroy it.
You have a perfect example of what would happen in the latter scenario right here in the U.S. from 2009-2016. What happened to GDP over that period? It barely grew at all.
You see a comparable example in Japan, where the Bank of Japan has a short-term interest rate target of -0.1% and a long-term target of 0%. Japan's GDP is lower today than it was in 1995, and its interest rates have been around 0% for almost that entire time.
With this information in mind, let's ask a better question: Are government interest rates a cause of GDP growth/retraction, or an effect of it?