Volume is how much work you do. Intensity is how hard that work is. In gym terms, volume is usually sets and reps, while intensity is load and proximity to failure.
For hypertrophy, volume is a major driver. More hard sets generally means more growth, up to a point. But that volume has to be challenging. Junk sets with low effort do not count for much.
For strength, intensity tends to matter more. You need practice lifting heavier loads. But even strength training still needs enough volume to build the base.
Most people do best in the middle: moderate to high volume with hard sets close to failure, and heavier work on key compounds. You do not need extremes.
If progress stalls, ask simple questions. Are you recovering? Are you pushing hard enough? Is total weekly volume too low? Or too high for your recovery? Adjust one variable at a time so you can see what actually works.
Volume and intensity are teammates, not enemies. Good programming gives both a clear role.