You can use cordova-plugin-ringtone to set an audio file as ringtone, notification tone or alarm tone.
Call the plugin JS function https://github.com/Hiraqui/cordova-plugin-ringtone#example-3 using browser object.
If your Android target SDK 22+ then you need cordova-diagnostic-plugin to prompt app permission before using this plugin. For how to implement this plugin in Construct 2 you can watch video tutorial https://youtu.be/aHbY7BkF8Pg