is there any way to increase the volume of my iphone 6+ earphone?

Hello tanybelle

Thanks for using Apple Support Communities.

To increase the volume of your headphones that are plugged into your iPhone, you will need to use the volume controls on the side of your iPhone.

When you’re on the phone or listening to songs, movies, or other media, the buttons on the side of iPhone adjust the audio volume. Otherwise, the buttons control the volume for the ringer, alerts, and other sound effects.

WARNING: For important information about avoiding hearing loss, see Important safety information.

Lock the ringer and alert volumes. Go to Settings > Sounds, then turn off Change with Buttons. To limit the volume for music and videos, go to Settings > Music > Volume Limit.

Note: In some European Union (EU) countries, iPhone may warn that you’re setting the volume above the EU recommended level for hearing safety. To increase the volume beyond this level, you may need to briefly release the volume control. To limit the maximum headset volume to this level, go to Settings > Music > Volume Limit, then turn on EU Volume Limit. To prevent changes to the volume limit, go to Settings > General > Restrictions.

Use Control Center to adjust the volume. When iPhone is locked or when you’re using another app, swipe up from the bottom edge of the screen to open Control Center.

Volume controls - iPhone

Take care.