I want to be able to see the volume level of my phone as a scalable icon that behaves just like WiFi and battery. If the volume is on full, it shows up completely white, empty shows up gray, etc.
Is there a default setting that I can't access (going into Volume on my phone's Settings causes Settings to crash), and is this even possible with an app?
By default the answer is a no.
Since changing the color of notification bar means modifying the system it can't be done by a normal application. Best you can do is an icon that can be added to the notification bar.
But there is a way if you are rooted.
Xposed Framework is a great app that lets users modify every single action executed at system level. You can use Status Bar Volume for what you want to have.
Thanks to Izzy for finding and sharing the name and link of the module and letting me using it in my answer
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