Yes—generally, curves are the most flexible of the three. A levels adjustment is roughly like a simplified curve with control over the black point, white point, and midtones. A contrast slider is simpler still, often acting like a broad global increase or decrease in tonal separation.

So in practice, curves can usually do what levels and contrast do, plus much more. The tradeoff is speed and simplicity: contrast and levels are quicker for broad adjustments, while curves give finer control but can be slower and easier to overdo.

That means you do not have to use the contrast slider if you prefer curves, but many editors still use it because it’s fast and convenient. Different software versions and workflows also make some tools more practical than others. In the end, there are often multiple ways to reach the same result, so the best choice is the tool that gets you there efficiently and predictably.