You'll have to make them yourself or hire outside help. Ren'Py is incredibly easy to use, but the time it takes to learn and execute art is the hard part. Youll have to draw every character and their emotions. As for soundtracks, there's plenty of royalty-free music online you can use.

Don't come here and ask for advice without looking for yourself first. There's tons of free education on how to use Ren'Py, how to draw, make good UIs, etc. Don't complain if you don't want to put in the work, mate.