I have checked main sources
And unfortunately I can not found other way than build library from source https://webrtc.googlesource.com/src
Is this correct way to receive fresh version of WebRTC library for Android application?
I have searched online for you.
jcenter is still available but read only, if the url is not working maybe updating the build tool would help.
webrtc source code is available to build. and i found that there is a webrtc sdk for android source code
so I searched webrtc sdk android and found this,
maybe you can use this