Boosting the volume on an iPhone can be useful in various situations, such as when in a noisy environment or when listening to music or podcasts. There are several ways to achieve this, depending on the model of iPhone you have.
On iPhones with physical volume buttons, you can simply press and hold the volume up button to increase the volume. On iPhones without physical volume buttons, you can swipe up from the bottom of the screen to open Control Center, then drag the volume slider to the desired level.