It is more difficult than you might expect.
The AZ-900 exam covers a lot of topics. As you can see from the official objectives list, there are about 100 topics covered on this exam. That’s a lot.
The good news is that the exam level is designed for beginners. So even though it covers a lot of topics, it does so on a beginner level. Each exam objective only requires you to “describe” or “identify” something, and not actually design or implement anything.
So anyone can do it. But it’s a decent amount of studying, even if you have some experience in Azure.