The answer is it depends..
If you need to run Windows for a specific application, you can try to see if that app works on macOS or you can find an alternative. If you can't, then you can see if running Windows in a VM might suit your needs. If you absolutely need to run Windows natively (for gaming for example), then you'd have to go down the Boot Camp path and partition your drive to make space for both macOS and Windows..
Installing JUST Windows instead of macOS on a Mac, while possible, is just silly IMO. You can buy a perfectly good PC (for cheaper) to do that..the clear advantage of buying a Mac is not just the hardware but also macOS..