Headphone Accommodations, which was introduced in iOS 14, improves the audio from your AirPods by boosting softer sounds and certain frequencies. This requires AirPods Pro or second-generation or newer AirPods.
Turn on the setting in Settings > Accessibility > Audio/Visual > Headphone Accommodations. To hear a sample, tap Play Sample, then adjust the audio to get a balanced tone throughout a variety of frequencies, a voice range for middle frequencies, or brightness for higher frequencies. You can also mildly, moderately, or aggressively augment quieter sounds.
You might want to experiment with playing music, podcasts, audiobooks, or other audio from your own library to see which settings work best for you. Alternatively, you may tailor the audio output by tapping Custom Audio Setup and answering a few questions. Your audio settings will be modified based on your responses.
The AirPods Pro adopts an in-canal design with three sets of replacement tips for small, medium, and large ear canal sizes.
Take an Ear Tip Fit test to find which of the three size tips will provide the best seal and sound.