Go to Sound Settings > Enhancement > Check "Loudness Equalization." This makes quiet sounds easier to hear.
A powerful, open-source system-wide equalizer that includes a pre-amplification filter to boost volume. Conclusion
If you only need a boost for YouTube or Netflix, extensions like "Volume Master" can increase tab volume safely.
It can be set to launch with Windows so your volume is always where you need it. Safe Alternatives to Boosting Volume