It can be enough, but you'll have to be actively managing your storage. The less storage you have, the more effort will be required. On the other hand, failing to manage/clean your storage is what leads to people "needing" huge amounts of storage in the first place.
My position is that the cloud can save your butt. Most people who backup their phones to a computer end up forgetting to backup. Inevitably, when something goes wrong (loss, damage, or equipment failure) their most recent backup was a year old.
The cloud is also a major convenience. If you do have multiple devices - iPhone, iPad, Mac or PC (yes, there is iCloud for Windows), it's nice to synchronize your data between them. The calendar event I create on my iPhone shows up on my iPad and Mac and can even be retrieved by voice command from my HomePod. The photos I take on iPhone are available for display on my 12.9" iPad screen and my 60" television via AppleTV. And so on.
Yes, the cloud takes a bit of learning, and the space you use in the cloud can become just as cluttered as space on a local hard drive, but overall I would not want to be without it.