Training to or near volitional failure is the primary driver of muscle hypertrophy, and rep range is largely irrelevant for muscle growth when effort is maximized.

Study: Neither load nor systemic hormones determine resistance training-mediated hypertrophy or strength gains in resistance-trained young men

When people train until they can't lift any more (volitional failure), it doesn't matter if they do 20+ reps with light weights or 8-12 reps with heavy weights - they get the same muscle growth. This study proved both approaches built muscle equally well.

Study: Low-Load Resistance Training to Volitional Failure Induces Muscle Hypertrophy Similar to Volume-Matched, Velocity Fatigue

If you push your muscles as hard as you can until you can't go on, your muscles grow — no matter if you do 10 reps or 30 reps, as long as you're giving it everything. This study found that lifting light weights until you're exhausted gives the same muscle growth as lifting heavier weights for fewer reps, as long as you're pushing just as hard.

Study: Similar muscle hypertrophy following eight weeks of resistance training to momentary muscular failure or with repetitions-in-reserve in resistance-trained individuals

If you push your muscles really hard until you're almost out of steam—even if you don't go all the way to failure—you still grow just as much as if you pushed until you couldn't do another rep. The study found both ways led to the same muscle growth.

Study: Resistance Training Load Effects on Muscle Hypertrophy and Strength Gain: Systematic Review and Network Meta-analysis

This study only included experiments where people trained until they couldn't do any more reps. It found that whether people used light weights for many reps or heavy weights for few reps, they gained the same amount of muscle - as long as they pushed each set to failure. This supports the idea that training hard to failure matters more than how many reps you do.