Control phone volume with broken volume key.
Are the volume catches on your device broken? Attempt Volume Slider, the volume button replacer.
Note
If the app isn't working for you especially on Redmi devices, please go into Settings or wherever you grant your permissions, and make sure Volume Slider For Android is allowed to DRAW OVER APPS > DISPLAY POP-UP WINDOW > PERFORM SYSTEM_ALERT_WINDOW > MODIFY SYSTEM SETTINGS.