You can create a custom Game Preset for your Stealth 700 Gen 2 Xbox headset in the mobile version of the Turtle Beach Audio Hub app, which is available here.
To create your new preset, open the Turtle Beach Audio Hub app. On the home page, tap the arrow next to the current preset.
Swipe left or long press on Custom to edit a new Preset
You will see the following. Adjust the sliders to your liking, and then tap Save.
Your custom Preset will then show up in the list of available Presets.